About two years ago, I changed the password on my FB account and stashed it somewhere. I deleted most of my photos and things that appear on my timeline. There were just enough folks I know, that I keep it around ... but I don't use it to communicate on a day-by-day basis.
I certainly don't want it on my phone.
But you know, if there's a separate Messenger app, I'd probably install it. Something that allows people on FB to contact me if they need to ask something, without sucking me into the Feed.