Probably going to be pretty low tbh. You have to play a fucking LOT of games to get anywhere even remotely high, and all those games are long as fuck and slow Qs to boot. Personally I started doing rbgs very often (like maybe 30 games a week or so, which is a ton of time considering Qs and game length)about a month ago and I'm still not even 2500, having never lost a single point of rating on the way up and starting from like 800 rating or so too. The grind is fucking ridiculous and I seriously doubt a large number of people are going to end up in the upper 2000s, and I even more seriously doubt that anyone is going to be able to actually grind this shit in like a couple weeks' time if the mount turns out to look cool.
Heh, try the OLD GRIND. Then complain to me : D