If speeds are throttled for e.g. mumble traffic, steam etc, one thing that TF2 does have going for it is that it's running on the same engine and ports as CS, which is highly popular, so it's reasonable to assume that if shit does get split up there will likely be a gaming package that will prioritize that kind of traffic (specifically thinking routing to ESEA/faceit will be ok, 3rd party servers might be fucked tho). Mumble might have some issues because it's open source and uses 3rd party servers, but something like discord will probably be fine so people might have to switch to that.
It still fucking sucks for everyone because I guarantee you'll have to pay an extra premium to get this.