This has been suggested multiple times, but BU supporters insist that their wacky implementation must force Bitcoin's hashrate onto their coin. BU wouldn't stand up in the marketplace as a separate coin, no investor is going to risk real money on something that is designed to be super-easy to fork.
And no investor is going to risk real money on something that cannont handle more than 200 millions transaction per year.
No investor is going to risk money if he will not have the possibility to withdraw his money without paying huge fees.