Trying, likely unsuccessfully, to move speculation of the two cards we know will be in the new set into this forum.
Some thoughts on ruins: We know the theme involves upgrading. Ruins sound to me like destroyed buildings or lands. The single-type victory cards have always been variations on buildings or lands. So, perhaps:
Ruins
Type: Victory
Cost: $0
0 VP
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When you buy a victory card, trash this from your hand.
This lets you "upgrade" your ruins into a better victory card, but still clogs your deck and interacts with victory card effects. I assume, if a card similar to this one is in the deck, there will be an attack card along the lines of "trash a victory card from your hand or reveal a hand with no victory cards. If you do trash a victory card, gain a victory card that costs less."
Some thoughts on shelters: Because these could replace estates, I'm going to assume they won't significantly alter the standard opening too much (as in, we will still have $2,3,4, or 5 to buy with and no actions to play). That would make shelter a victory card as well. Or, if it were to be a victory-action card, it could be an action that is useless at the beginning of the game, but that gets more powerful as the game progresses. For a card that you start with, though, I cannot imagine it ever gets too powerful. With the "trash" theme in this set, my bet is on a dual-type victory-action card that interacts with the trash pile (and has a +action at the top so that it doesn't become a terminal action). At the beginning of the game, it functions is no differently than an estate but as cards get trashed, it starts to do "something." The question, then, is do you trash these early to get your deck moving quickly or hold on to them until the trash pile fills up. Perhaps:
Shelter
Type: Victory-Action
Cost: $2
1 VP
+1 Action
You may gain a victory card from the trash pile.