Earlier quoted context omitted.
The loss of domain fronting as a viable strategy means that it will be possible to censor Signal in areas where the service was previously working.
It's a warning to not break terms of service. The strategy still works, but it's against TOS of most hosts so it was never really viable. Time to look for another option then, like any other technical challenge. I support Signal's work here but unfortunately we can't just enlist every other business to help (otherwise censorship wouldn't be much of a problem in the first place).
That's the plan. This is covered briefly in the second-to-last paragraph.
> so it was never really viable
Signal remained running for more than a year and a half in several countries that were actively trying to censor the service.