You speak as if the UK is the only hotel in Habbo Hotel. They are probably going to know its going to be a hit from the statistics from the other Hotels. It sure is a big change from Habbo, it's been eagerly anticipated for a long time, everyone has always asked for music on Habbo. The staff are a little over enthusiastic about it, but then again, they are playing games with our minds trying to get us excited with them.
Habbo isn't continually having updates to keep the users, they keep their average users with or without updates, updates are to continue the fun on Habbo, more activities for its users which generally means more money raking in. I would hardly say Sulake is deteriating, their franchise just keeps getting bigger and bigger, and with the release of Habbo music, probably will boost more bands to come on the site, with the possibility that they will be able to sell previews of bands tracks, I don't know but sounds like a good possibility, this all means more publicity for the site and overall lots more money being raked in.
I won't be using trax, I don't use Habbo much anymore, but I imagine it will be a big hit on the hotel