I think it's actually not bold at all to call Squire a power card. +2 Actions, +$1 for $2 is pretty reasonable to begin with, and when you add in all the other things it can do for your engine (+2 Buys, trash for an Attack) OR for your alt-VP rush (Gain a Silver, +2 Buys again) I think it's entirely reasonable to view this card as on par with the Lighthouse/Courtyard/Hamlet trio, and very possibly better than them.
Here are some bold predictions that I'm probably not going to test for awhile yet, since I'm trying to take a break from online Dominion for a little bit:
*Poor House is going to be better than you think. Obviously it needs an enginey setup with trashing and +Action and +Buys, but when those things are around it will be an amazing way to ramp up your buy power quickly.
*Wandering Minstrel is going to be one of my favorite cards, even though it kind of defies the typical Village theming. I've been waiting for a minstrel-themed card since day 1, and tacking that theme on to a Village that fishes for Actions is just gravy. I think it is probably going to be the best $4 Village, certainly better than Farming, though Worker's may still have a case.
*Mercenary is not going to be all that great. At some point, you're going to run out of things you want to trash, even with all the DA trash synergies, and it's an "if you do" clause, so it's not even like you can discard down to nothing and try to trash to get the attack. I'm sure it will have its uses every once in a while, but most of the time I bet it's actually not worth it- or even when it is, you'll only be able to play it once or twice.