We can say with confidence that this will be a one stop race. For long time readers of The F1 Newsletter, 
you will remember from last year’s edition that the tarmac at Sochi is famously easy on the tyres. So much so that even in the 2016 race, where they used the high degradation tyres, everyone ran a one-stopper. A no-stopper would definitely be possible this year, but the regulations require at least one stop.
The difference in 2017 is that Pirelli is bringing a softer compound tyre. The purple Ultrasofts will now be available. Expect teams to qualify and start the race on the Ultras then start and switch to the Softs or Supersofts to finish. There isn’t much performance difference between the Softs and Supersofts, but the Softs are expected to last a bit longer. Last year the Supersofts were good for 20+ laps and the Softs went 30+. That extra durability in the Softs could allow a team to attempt an early, aggressive undercut to gain a position. For example, Vettel could pit after 10 laps, put on a set of Softs, run a very fast out lap on his fresh new tyres, and end up ahead of Bottas, who would pit a lap later (and consequently, did that extra lap on older, slower tyres).
We’ll see what happens when the lights go out.