Reno decks can be a lot of fun, but they're not really that competitive because they are less consistent than most other decks. Also, they're old.
A new mode in constructed would be fun, but I don't know if there's a big enough player base to justify it, and there's not really enough cards and archetypes to really dramatically shift what's played. A mode with less cards would yield similar archetypes, but with holes in them from the smaller card pool. Not really cool enough to justify a whole other ladder system. But I could be wrong.