Yes, interesting observation. While BU's numbers seem to be inside the normal statistical variation, Segwit acceptance has definitively increased.
I think much will depend on what F2Pool decides to do (third largest pool as of March 26). Until now they don't signal neither for Segwit nor for BU. I have no recent statements from them, but they seemed Segwit friendly, although they said they would activate it first in Litecoin (where they haven't begun signalling it yet). Maybe their gamble is to stay with 1 MB a while more to drive the fees a bit higher first.
they're playing a dangerous game either way.
They're chocking the network and driving users away form bitcoin.
Even if current holders keep holding, new adopters seem to prefer altcoins over bitcoin.
Prefer alts in case of what? Usage? Probably not! Quick profit? Very likely!
So the new adopters are more speculators and traders! No problem!
Once they see that you can also make profits with a crypto over a longer period of time than just short term with alts where the risk to lose big is as big as to make big profits, they will shift some of their investments into Bitcoin! No doubt!
Bitcoin market share compared to total cryptocurrencies dropped from 95% to 65% so this is a big drop.
It's pretty worrisome that bitcoin lost so much ground to altcoins, because the network effect is the main reason people consider bitcoin as the best crypto.
Bitcoin can only stay at the top if it keeps the trust of investors, if investors lose trust, bitcoin will crumble and altcoins will take their share, and it will be very hard or even impossible for bitcoin to recover.