It probably won’t, and if anyone knew how they could break, then they wouldn’t break. But maybe it’ll turn out that some assumption made about how to create subscriptions and how they persist turns out not to be true.
Things aren’t always as they seem, and the obvious solution is sometimes wrong. It’s a reasonable bet that the stuff you set up now will work forever, but it might not. And right now, it’s too soon to make any promises. If it won’t be that big a deal for stuff to be broken for a day or two if you have to fix something up, go for it. If you’re going to lose $10,000/hour if you’re suddenly not able to sign up new people to your thing, well, you should be very careful when you do upgrades.
Me, I’m planning to start using the plugin to charge people for some recurring services. If something happens such that people get services for free, or I have to fix something up by hand, well, that won’t be that different from my current experiences with WooCommerce and Gravity Forms.