>>25006501
>standard 3-set block, 2 big 1 small
Er, no? Standard 3-set block is one large set, followed by two small sets.
It is also important to note that, after the Great Aurora, Lorwyn and Shadowmoor no longer alternate over long periods of time. We don't know the exact nature of the fusion, but there is no longer the massive shift that led to the two small blocks. Lorwyn and Shadowmoor are now one world.
So, we're looking at a Large-Small-Small block, which focuses on tribal and hybrid mana. The tribal focus would probably be less than in original Lorwyn, as Shadowmoor was more successful in market research, but still present.
Planeswalkers are a limited resource, so we probably wouldn't get five new ones in one block. There would, in fact, be strong pressure to have at least one of the Lorwyn Five return, much as Return to Ravnica revisited some of the same guild leaders. At a guess, Ajani (looking for peace after the events of Alara) and Garruck (looking for peace after dealing with his curse).
The real question, of course, is whether the tribal type would return. The decision during Innistrad was that it can get too pervasive, but there's the obvious counterargument that it was a large part of what made Lorwyn unique.
Persist, kinship, chroma, and clash would not return, and I'd have my doubts about wither. That means a lot of mechanical space is undefined, and it really rides on what the central conflict of the block would be.