In the short term there are some interesting possibilities as Nicolas and Lorraine were deeply entangled in the web of alliances surrounding Charles the Bold of Burgundy. If Nicolas survives Charles the Bold probably continues his campaign in the north adding Frisia to his conquest of Guelders. OTL the campaign was cut short to deal with the Lorraine succession. The conquest of Frisia has import to Charles' simultaneous negotiations with Frederick III to be crowned King of the Romans. Frederick was apparently willing to give him a crown but not an Imperial one. So perhaps with Lorraine firmly in his camp under Nicolas and the recent conquest of Frisia complete Charles could secure for himself the title of King of Frisia, though something lesser like Lord of Frisia is probably more likely for all the reasons Charles failed to get a crown OTL. But a Lordship of Frisia with some kind of vicariate over the Low Countries would have ramifications when the Burgundian line ultimately dies out.
But as things advance it's not guaranteed that Nicolas would remain in Charles' camp. He had been earlier wooed to the French side with promises of marriage to Anne of France until Charles tempted him with his own daughter Mary. Sadly for him Louis used Anne and Charles used Mary insincerely as bait with neither side really willing to commit to the marriage. Charles apparently made Nicolas renounce his engagement to Mary in 1472 after the conclusion of the campaign against Louis, ie when he wasn't of immediate utility and when Charles needed once again to use Mary as lure to get his crown from Frederick. So if Charles gets too arrogant I could see Nicolas defect back to France and marry Anne before she marries Peter of Bourbon. Bona of Savoy was married prior to his OTL death so I don't see why that would change.
I could see a scenario where a stronger Charles, still failing to be crowned King of the Romans, obtains a crown or double crown (Burgundy, Frisia or Burgundy and Frisia) from Frederick in 1473 with the betrothal of Mary and Maximilian. Charles ensures that Savoy and Lorraine fall within the territorial vicariate of his new Kingdom. This angers Nicolas enough (loosing out on Mary on top of having to submit to Charles) that he promptly defects to Louis and renews the betrothal to Anne. Charles of course invades Lorraine and perhaps the rest plays out like OTL with Charles' enemies ultimately getting the better of him. I think his unchecked ambition will always be his undoing. But Nicolas comes out of the 1470s still Duke of Lorraine and Anjou and Count of Provence with his previously strong neighbor, Burgundy, chastened and perhaps in a succession conflict. Then in the early 1480s you have a child, Charles VIII, on the French throne, the Habsburgs trying consolidate their hold on Burgundy and so the way is open for Nicolas to extend his power and influence.
Alternatively if the wedding and coronation fall through as OTL perhaps Nicolas holds out in the Burgundian camp. Without the problems in Lorraine Charles could live longer than OTL, obviously no Battle of Nancy, but ultimately he has to settle on a marriage for his daughter by the close of the decade before she becomes too old and thus a less desirable marriage prospect (a serious concern considering his enemies had been spreading rumors for years that she was infertile or had some other condition that would prevent her from giving any prospective groom healthy children). So then a lot depends on the intransigence of Frederick and Charles. Maximilian is still the best candidate since his father can give Charles something no one else can, a crown and greater power. But Frederick absolutely refused to make Charles King of the Romans and Charles' conditions for a lesser crown were too great. So either they reach a compromise and Mary marries Maximilian or Charles ultimately looks elsewhere and Nicolas is still probably the best alternative. Given that the only others considered OTL who would still be candidates in the mid 1470s would probably be Nicolas, Francis II of Brittany, the Dauphin Charles and maybe Frederick of Naples, Philibert of Savoy and Philip of the Palatinate. Nicolas brings more to the table than Francis, the Dauphin is too young and the enmity between Charles and Louis would probably scuttle such a marriage and the latter three were never really seriously considered. So Nicolas stands a good chance but really only if Frederick refuses to cooperate.
If in a third scenario Nicolas marries neither Anne nor Mary he probably looks further afield in an attempt to advance his own dynastic interests. Perhaps as a way to bury the hatchet with Aragon he weds Ferdinand II's sister Joanna of Aragon (OTL wife of Ferdinand I of Naples). Or perhaps a daughter of Eleanor of Navarre as prelude to a move against Aragon. Anne of Savoy (OTL wife of Frederick of Naples and cousin to Charles VIII) could serve as a marital alliance with France while also opening the alpine passes to an Angevin army should he want to move against Naples.
Certainly the late 1400s are very different in any scenario. Charles VIII's claim to Naples was as the Angevin heir through his grandmother Marie d'Anjou, but with the Angevin male line continuing he has no claims in Italy. On the other hand given a marriage to Anne I'm not sure that Nicolas, or more likely his son, would be able to muster sufficient forces to successfully invade the peninsula, certainly not in the manner that Charles did. Nicolas would also have claim to Aragon through his great grandmother Yolande of Aragon and John II of Aragon was quarrelling with Louis XI over control of Roussillon through the 1470s, since it had been pledged to France but Louis would not let him redeem it. If Nicolas secures a role in the regency of Charles VIII perhaps he can claim Roussillon and move against Aragon again. It would also be interesting if, assuming Francis II still only has daughters, Nicolas is able to marry his son to an ATL Anne of Brittany. It would shore up Angevin territories in the west of France, though his collection of fiefs is still pretty unwieldy. I suppose if he can't secure either Naples or Aragon, and either would be tough, the Angevin line will, in the long term, be not much stronger than the houses of Orleans or Bourbon.
Given the alternative of a marriage with Mary of Burgundy then Nicolas has a substantial realm, larger even than Charles' but he's probably the mutual enemy of Louis XI and Frederick III. If he can survive until their deaths he then has some breathing room. Perhaps he exchanges the Duchy of Anjou for clear title to the Duchy of Burgundy or perhaps given some outrageous success in a Mad War equivalent he secures both and the Breton inheritance to boot. He should then have enough time to secure his dominions allowing his son to muster a force for an invasion of either Italy or Aragon, probably the former. But he'd be opposed by Aragon and tacitly by France and the Emperor who would both be fearful of further Angevin aggrandizement so its hard to say how successful such an endeavor would be.
Ultimately the problem seems the same, without securing a crown of their own outside of France and the HRE the Angevin 'Empire' may prove as ephemeral as its 12th century namesake. A collection of fiefs, especially one straddling the borders of France and Empire, would lack the cohesion for true long term stability and growth. It would be really fun to see the Angevins inherit Burgundy then take Naples then go own to gain the Imperial crown after Maximilian, make themselves Kings of Burgundy, Frisia (Low Countries), Lombardy and Naples and so secure a power base for themselves within the Empire that could sustain their dynasty. Then their collection of territories is analogous to the Habsburgs' realms and that dynasty ruled the Empire for centuries. The OTL network of alliances would certainly be thrown off. The personal union of Castile-Aragon under Isabella and Ferdinand would probably retain the traditionally pro-French policy of Castile in opposition to the Angevins. So rather than a Habsburg marriage there may be a series of Franco-Spanish matches by century's end. And an alliance of France and Spain, if it could be maintained, would be a serious threat to the Imperial Angevins.
