I think there's a 0% chance that Islam fights Topuria next. Islam has defended his belt 4 times, two of those were against a 145er. It would make no sense for 3 of Islam's 5 defences to be against 145lbers. Regardless of how cloudy 155 is.
Meanwhile Ilia has only defended his belt 1 time, with plenty of exciting matchups. Lopes vs Topuria would be an absolute banger. You move up once you've cleared your division, Ilia has only just gotten started.
What I see more likely is Islam moving up to 170 if Belal loses the belt.