Stations will have to make a calculation: how much will we save by switching off our analog transmitter vs. how much ad revenue will we lose due to viewers who don't have digital TVs or converter boxes yet?
Some stations have made that calculation and decided to switch early. In my area, KSTR and KXII have already shut off their analog signals permanently, and we haven't even reached the original transition date yet!
As for digital signals increasing their power, that'll be up to the FCC. I expect they'll accomodate requests to increase power as quickly as possible, as adjacent analog signals are shut down.
I doubt there will be another delay. Despite what you may have read, the major reason for the latest delay wasn't that "some folks still weren't ready;" it was that the DTV coupon program had run out of money. That should be taken care of soon and it's not likely to happen again.