The impending doom of G+ is unsurprising, but it makes more urgent the need for me to find a better way to hold discussions online, rather than merely making blog posts into the void. Facebook is for personal friends and family only. Twitter atomizes conversations into individual tweets, making them hard to follow, is overrun by robots and spammers, and has been welcoming nazis at its highest levels (https://mashable.com/article/twitter-ceo-jack-dorsey-kept-alex-jones-on-twitter/) while shutting down left-wing academics (https://www.chronicle.com/article/Why-Did-These-Scholars/244686). Mastodon is like a combination of the bad aspects of twitter (no continuity) and Google+ (nobody home). Instagram really only works for snapshots. I've been using G+, despite its limited audience, both for smaller postings to links elsewhere and as a host for comment threads for my blog posts. Is there something else I should be trying?
Google is shutting down Google+ for consumers following security lapse
It is possible to "follow" someone on Facebook without being a friend.
I'm on Twitter these days; I often post links to longer blog articles there, but also post multi-tweet things, riding roughshod over the stupid 280 character limit. I don't get many trolls, maybe because I don't talk about politics. I have fewer followers there than here, but apparently a lot more people who actually read what I write.
I’m something obvious at mathstodon.xyz, but I’m not there often.
Also the story of the blocking of Kevin Gannon seems pretty mild: Twitter claims that it was a bot mistake and that they quickly reopened his account. This sounds plausible since as you yourself say, Twitter is full of robot spammers, which they presumably need to combat aggressively.
Compare that to what YouTube is doing to Prager U: https://www.prageru.com/playlists/restricted-youtube
Hmm. Looks like Blogger is on G Suite. I’ll have to check out whether that still looks viable...