I'm surprised that Sinn Fein are attending the coronation - this seems to indicate they really are moving away from their republicanism towards a generic centre-left welfare state platform.
If the TUV takes votes off the DUP from the right, it’ll scare them stiff, and encourage them to obstruct further. If they lose votes to the UUP and Alliance (both of whom could conceivably overtake them in several unionist regions) it could be something of a wake-up call, and make them a little more amenable to cooperation.
Thanks to Ireland's reasonable ranked ballot system, the last assembly elections came as a real shock to the TUV: with 7.6% of the first vote, they obtained ONE out of 90 seat (1.1%), due to how radioactive their party is to transfers.
If frustrated unionist voters have an ounce of strategic reasoning, they'll lend their votes to centrist parties who will actually get elected and reopen Stormont.