Honestly, I'd put money on them using the "team with the most players at the end" mechanic that they explained at the very beginning. They haven't really gone into too much detail beyond that, besides a universe or two using that as their "strategy" to win.

I'm betting there will be shenanigans surrounding that, such as Jiren knocking both Goku and whoever else is left off at the same time, but right as they're starting to teleport to the stands, the time ends, causing Jiren to lose. Or something equally cheesy (not in a bad way, just roll-your-eyes-"oh, Dragon Ball"- style).

Might not happen, but again, I'd put money on it. A lot of people are throwing around evidence of "they told us A LONG TIME AGO what would happen and it did" theories around, and this seems the most simple and plausible, in my opinion.

What do you guys think?