I am afraid this may be a major blow to the whole porting efforts, which have only been getting bigger over the years, and also developers of native applications. Those developers and/or porters greatly contribute to the Sailfish ecosystem with their work, and overall make it more robust and more attractive as more devices or applications are available. There may be consequences of this on Jolla and Sailfish itself, which I guess have been weighed before coming to this, but this is very concerning.
I hope the reception by the developers can help reconsidering the decision, or that proper and equally convenient alternatives maintained by Jolla can be proposed in return of what the porters and developers made of Sailfish. Self-hosting and building locally sounds like a huge pain that would surely discourage a good fraction of those key community people. They are literally already saying it all over the various Telegram or IRC servers, or here; this can’t be overlooked.
[Edit] Well, a significant contributor already left the boat and moved to another OS today with an announcement on his repository. :\