Hangouts seems to be a core part of G Suite — it’s integrated into Calendars, for one thing. I don’t think it’s going away. (I think they also just increased the maximum number of participants?)

YouTube Live almost certainly requires AdSense to offset the cost of running live streams. I’d be inclined to pay for a solution — and/or find a way to run something inside an institution.

In general, over the next few years, I think educators are going to need to stop relying on free services like this and start rebuilding institutional infrastructure. There shouldn’t be an expectation that everything will continue to be available to use cost-free, particularly as venture investment begins to dry up.