Most if not all public relays are hosted on rented servers. Scaling will not be a problem. They might lower write limits to limit cost, but kind 1 and 0 events will be unaffected since they take up virtually no space. The first to fall will be the free media hosts like nostr.build but this will honestly be good imo because it will result in a relative increase in attention to all the people who pay for hosting or host themselves. It will mean that the million new kids won't completely take over the space, but they will be subject to the influence of the based MFs here that host their own shit.