In this scenario Gruffudd Ap Llywelyn manages to stay both alive and in power over a unified Wales as King at the time of the Norman Conquest. Can you imagine him managing to annex all lands west of the river of Severn plus Chestershire and managing to defend those lands against William? I can. In this scenario, he passes the throne to any eldest so he has and Wales at last develops into a unified Kingdom having regained the fertile lands between Offa's Dyke and the Seven. I imagine a capital eventually being established in the form of Hereford, Shrewsbury or Chester. Offcourse in the end, Wales would have to be conquered though perhaps not before the end of the middle Ages?
Just some more thoughts:
[FONT="]After a narrowly unsuccessful campaign following the death of Ælfgār, Harold enlists the assistance of his brother Tostig in a larger scale operation to crush the Welsh king decisively. The combined operation began at Rogationtide 1063 (25-28 May). It ended with Gruffyd being killed by his own men (5 August) because they lost confidence in a king who failed as a military leader. (Some sources say he was killed by a Prince from a rival line, Cynan ab Iago.)
What effect does not killing Gruffyd have on the Saxons? What does it do to Harold’s reputation as a warlord? Even if the search and destroy mission wasn’t ordered by the Confessor I can’t see Harold leaving it unfinished. The survival of Gruffyd might just butterfly away a 1064 boat trip that ended with Harold as a ‘guest’ of William. It may also have consequences for the 1065 rebellion against Tostig.
But assuming events play the same as OTL and a successful Norman conquest happens I still can’t see Wales achieving what you imagined. It would be nice…
Further on those waiting for Gruffyd to fall: his half-brothers Bleddyn ap Cynfyn and Rhiwallon, who became Kings of Gwynedd and Powys; Maredudd ab Owain who became King of Deheubarth (and his brother Rhys ap Owain); Cadwgan ap Meurig who became king of Morgannwg and Gwent. There is also Caradog ap Gruffydd, who is active in Morgannwg and Gwent, whose father was killed by Gruffyd ap Llywelyn.[/FONT]