edit: Rewrote
Most likely scenario; Greece votes yes, Tsipras calls elections, minority government is formed with pro-asuterity parties, Troika is happy and might even give a better deal to boost the pro-austerity leader (all they have wanted is for Syriza to be ousted). Deal signed, but it will come back to bite them later because austerity won't work and anti-austerity will continue to increase especially outside of Greece such as in Spain.
Who knows how the markets will react. Feels to me like it's going to last a long time. The real problem is not even Greece, it's the Troika; they will never be able to change their position for domestic political reasons, and Greece will keep its foot in the door until they get shoved out, but that will send a very bad message about the union itself.
I'm all invested in VUG, VEA, VNQ (got hurt on that one), and BLV. I still hold some old tanked stocks, mainly DDD, SSYS, and SCTY. But I'm not putting my money in anything except ETFs anymore. No more short term thinking.