Battletech could be amazing, but I doubt any company will give a team enough time to do it right.
There's actually a pretty high demand for a mech game, especially an MMO / MMOFPS style game with mechs.
I don't think it has to be BattleTech, Chromehounds or Hawken, it could be a new IP for all I care.
Though all of these ideas will suffer from IP Hell in the end.
'IP Hell' is what I call when the rights are sold off to many companies, for example: SWG - LucasArts / SOE's partnership added a level of complexity that made it impossible to make a game like it again, or to bring that game back in any way.
Actually, IP hell is why I don't think any game should really be made around an existing intellectual property. The risk for the IP holder, or a disagreement between rights owners and development studios / publishing teams are exactly the reason why that MMOs like that fail. Not the fact that it's perceived as a cash grab, though that doesn't help.