4.3% hashrate is a good start, but if we add a Bitfury, thats another 7.9%. But the condition as far as I remember was that the Core devs must add the UASF code officially within the next Core release.
If we manage to get Bitfury on board then things get really serious because we enter the 10%+ zone.
Anything beyond 10% is interesting to see because snowball effect beggins.
if that is the condition then it will already doomed because core dev tema is all against UASF, just check their opinion on the matter
i thought that the UASF don't need core dev to do anything, they just rely on node to force segwit