I assume that at least some of the items on this list will be saved for season 5. For instance, I don't imagine we'll see anything in the Wall storyline beyond Stannis arriving to defeat Mance's army. They can save the stuff about Jon becoming Lord Commander and Stannis and company settling in at Castle Black for next season.
It does still seem like the whole finale will have to consist of a series of brief climaxes for each storyline, with probably the bulk of the time devoted to events in King's Landing. But I feel like it should mostly fit.
My only big question marks have to do with how they'll close out the Arya/Hound and Brienne/Pod storylines, which seem farther from a definitive endpoint than the other plot threads. But, then, I didn't expect those storylines to intersect this year, which seems from the previews to be what's happening, so perhaps they've got a concise resolution in mind that I never really considered.
One thought I had is that maybe we don't get Arya on a boat to Braavos at the end of this season, so that the writers can tease the idea that Fake Arya is Real Arya at the beginning of next season.