This is one of a possible result. RE:START can just be as empty as Thor and Chaos. It's up to WP how they want this new server to be.
Actually I meant about mechanics.
I honestly won't be trying to find out how it'll be or how many exact players it'll have. I do know for a fact that TH has a huuuuuuuuuuge playerbase so it'll definitely has way less players.