Hmm. I like musicals a lot. There's a lot of great examples of musicals. A musical in this format could work, afterall the thought back then of a rock musical sort of blew peoples' minds and The Who pulled it off. Tim Burton took it to the next level teaming up with Danny Elfman and bringing us Nightmare Before Christmas. Even Matt Stone and Trey Parker managed to get away with making a South Park Bigger Longer and Uncut a musical (and I thought it was brilliant, haha) Les Miserable is still popular and Rent - which is more or less a modern day take of opera La Boheme - helped make stage musicals popular again. The list is pretty long.
That said as musicals in this format could work, musicals are very niche and can be a hard sell. There's a couple of key things that are integral in having a successful musical and the same goes for most other entertainment - it has to be creative and innovative, it has to have some heart so people can connect, and it's gotta have style, relevancy and damn good overall delivery. Tim Burton's take on Sweeny Todd (although I liked it for it's Burtonesque uber goth cinematic qualities which I'm endeared to) was highly anticipated but for some reason felt lacking to me in a lot of ways. I couldn't connect with anyone except the little boy and I also felt he was the only one in that film that could truly sing.
So yeah, back to the Chems. I honestly think they are good enough at what they do, that they can pull off most anything they wanted to musically pursue. But as far as musicals go, personally I think it runs the risk of backing themselves into a corner and putting them in some kind of niche. Something they want to avoid as they've expressed in various interviews over the years.
I've also read that Tom and Ed don't want to pursue doing soundtracks. I know it goes against the grain of what they say but I would love to see them try. I can see them really excel and put their heart into a project like a soundtrack. I watch a film like Blade Runner and Vangelis' music is such a perfect fit, perfectly illustrating a symbiosis (in the most positive way) between film and score. It sets the mood and breathes a fascinating life into an already fascinating story and imo a most beautiful piece of cinematic genius.
Not keen on a Tom and Ed sitcom. But I'd be all over the idea of them doing voice overs as they did once express an interest in guesting on the Simpsons.