Thats exactly what BU is doing too. There is no activation code or threshold for BU. There is a suggested threshold of 75%, but that is not final and the current implementation has no activation code, so everyone will need to upgrade when that code is released. BU miners signalling is pretty much the same as the current uasf uacomment crap.
lol
all nodes that are ok with dynamics and REAL mainblock growth have the code there already. (my node has variable limit right now. i can change it at runtime and not need to download anything later)
no need to download a new implementation later for those that are already dynamic ready.. no need to play around with resyncing no need to change the network topology no need to get people to move to different keypairs.
its a simple. if there is a safe majority to not cause much fuss of orphans or node drop off.. pools just make bigger blocks. right at the point its safe to.
yet those wanting segwit WILL need to download something AFTER activation, ven if they have v0.14 they will still need to be spoonfed another version if segwit activates
blockstream made many foolish statements
"its ok sheep you dont need to upgrade, be happy to live in the cesspit"
"its ok everything is compatible if you accept the fact you become reliant on a tier network"
"when activated everything is fixed and utopia for everyone"