Mastodons share of the AP network fell to ~70% the last few days alone, due to a huge influx of users to Pixelfed (fleeing from Instagram). I myself run my own GoToSocial server at home, so I am doing my part to increase the diversity of AP implementations :)

I have also been thinking in the lines of a generic "all-in-one" client. The only reason this is not common yet, is old habits from decades of captivity in silos. I believe we will see such clients developed in the next few years.