Not just speaking technically but economically. As user number mount up their post is just going to add up. I know instaces may distribute user, but server space isn’t going to go down for anyone. It just seems like built to fall.
I’m running an instance, on local home fiber that I’m already paying for (30€/m around 700Mb up for real, 2x2.5Gb down theoretical) so no problem today, at all.
Don’t make the error thinking today’s tech will linger, we will most probably have better and cheaper hardware in the future, but also smarter algorithms dealing with it all, remember it’s a first try and can only get better.