It does certainly sound like Platinium will take any form of work, even if it means creating a sequel for another company.
However, I believe that if SEGA or Nintendo would want another Bayonetta game to fill out the universe that little bit more, I can bet that Platinum would want more money to do it, since doing more of the same doesn't look like something they would want to be known for.
Rising was probably an offer Konami gave them due to how slow development that was going under Kojima, but I don't think they would like to do more of them in the future.
Either way, I mentioned in the past that I am not the biggest fan of Bayonetta, but I certainly did enjoy the gameplay and will be buying the game as soon as a release date is announced. It may not be much, but my sale will hopefully keep Platinum in business and will help them make more games in the future. ;D
I can see how disappointing it is to have to buy a Wii U if you're desperate for it, and will segregate the fanbase, but given Nintendo's funding it, I shall take that over SEGA's cancellation any day.
I honestly have no clue on the cancellation either, especially when they just announced another Shining game (it's on consoles) that I believe didn't sell so well on the PSP last time? (probably due to the debacle of the whole Youtube thing). You'd honestly think that Bayonetta was a more popular franchise than Shining? Especially when the latter doesn't have much chance of being localised in the West ever again.
Sorry for the rant.