A more successful 1848, in particular if the Sardinians are more decisive (Carlo Alberto lost a lot of time, first before he decided to cross the Ticino, and worse even when he stopped in Milan). It might end up with Lombardy annexed to Sardinia, Manin resurrecting the republic of Venice and consolidating it, the former duchies of Parma and Modena joining together with Bologna and the former legations of Romagna (plus maybe Marche and Umbria) in another republic (let's call it Repubblica Cispadana, so it would be another resurrection) and the Grand-duke of Tuscany keeping his troops (by choice or otherwise) on the field.
The problem might be the Latium (the remaining portion of the Papal States): if Pio IX goes for a counter-revolution similar to OTL, it would end up again in establishing Repubblica Romana (which would be much harder to estirpate ITTL, given the Italian successes in the north). Let's assume that in the frame of a much more successful Spring of the Italian People Pio IX does not acquiesce to the most reactionary and conservative faction of the Curia, upholding the constitution he granted and continuing to implement liberal reforms (very difficult, he'd have to accept the territorial losses in Romagna and Central Italy). At the same time he declines to accept the presidency of the Italian Confederation, as proposed by Gioberti, and also keeps out of the above-mentioned North Italian Confederation.
Ferdinand of Two Sicilies also keeps out of the Confederation fearing the exportation of liberal ideas in the south and Sicily (this is much more easy).
The Confederation is there, with some doubt about the borders with the surviving Habsburgs (if they survive): Trento may become Italian, Trieste is a bit more difficult (but if the Austrian empire fails, it is a concrete possibility).
It may also be somehow unstable, given the presence of two quite large republican states, but who knows?