In Skeleton animation software. As far as I notice, there are few in the market out there, include spriter pro. This is great choice to have a new, robust skeleton animation software to have it right now. However, it has to be really eye-catching to make customer move away from their comfort zone(the software their are familiar with).
Spriter2 and Alchemist seem really powerful, and it is really great to have official support in multiple engine. But almost all of the engine that planned to support which already had a lot of choice to choose with. If I am indie dev, choose to cooperate with another people for art asset, I will consider whether the software support the specific engine I am working on and is that product stable enough to avoid to break the project and waste times. If I am artist, choose to cooperate with another people to make a game, I will more likely to choose the product I am familiar with.
Maybe I am wrong, but If spriter2 will support some engine that still lack of solid foundation that need 2d skeleton animation software to support with. Those devs will have no other choice but choose spriter2 as their animation tool. And Godot, which just recently upgrade to 3.2 version and it will be long term support version, seem really the best choice out there. I know there is difficult to handle the project and finish official support as the same time. But hope this suggestion will help.