Yeah, althought HHH is a beast I did not see that coming. He will lose eventually, but I think he already is relatively safe on 1st place, there'd have to be a cataclysm for him not to win now.
The way the rating system works on the seasonal ladders, everyone's rating will continue going up for as long as they remain in the season. Previous seasons have seen ratings above 3000, but a no loss season would be higher than previous records, obviously.
Ben's there. I think the highest rating is something like 3006 (haven't checked so may be wrong). Obviously the fewer losses you get and the more wins you get the higher it will get. I'd expect top ratings to go down in the seasonal ladder as more people improve and so on but that doesn't seem to be the case (quite the opposite).