If it's better, Then they have improved the ecosystem, and the developers and users will follow. If it's worse, then we can hope they will switch back, or they will lose users/developers.
The concern is a mixed bag... splitting development on something that may or may not ultimately win.
But mixed bags lead to innovation more than having one true way. Ideas from Mir and Wayland and X can lead to all three of them improving more then if only one or two of them were viable. However the lack of focus may slow individual development.
TL/DR Worst case is still not horrible, so long as Canonical recognizes it.