Currently, there's no entrenchment, as the apps are open source and there are self-hostable servers. You can easily get your data out and even continue using the apps indefinitely (the whole database stays locally in the app, offline; you just loose sync unless you self host a server).

I say that because that is the minimum bar for any alternative. I use them and am not panicking yet, but if I was starting from scratch, I would be cautious about choosing them.