All valid questions..
Do you realize that after SegWit, miners may collude to roll back to non-SegWit? Do you realize that every previous SegWit then becomes a real 'anyone can spend' transaction? Do you realize that if this is done, the colluding miners may claim the value stored in these 'anyone can spend' transactions?
If they did - Bitcoin would be OVER anyway. And the bitcoins would hold no value. They may as well hard fork back to the BUG where you could print Bitcoins for FREE..
There is a way to get rid of SegWit without this
doomsday scenario playing out.. Everyone just has to send the money BACK to normal addresses before the HARD FORK. (All though all trust would be lost - and BTC would probably be dead..)
Do you agree that this rollback/theft may be an incentive for miners to act counter to the intentions of the rest of the Bitcoin participants (whether or not sufficient to entice them to do so)?
Yes - But only in a completely self-destructive Mad-Man way.
Are you at all concerned about this possibility?
No.