I almost forgot about those features. I think they’re pretty solid.
Revision history for me, personally, does a lot. Especially if does exactly what Google Docs does. (Seeing what changes have been made (which are a different color font), undoing revisions, and restoring to select ones, etc.)
Google Calendar, recurring tasks, and true offline mode are something that I could see myself using as well. The main thing with the reminders and calendar integration is that it needs to work reliably (and on mobile, with having persistent notifications (probably Android only) and notifications that don’t go away until you’ve read every one (basically generating a new bundle of notifications after one has been read, like Telegram) would be great).
I guess another feature that would be useful is notification pinning, so that way they aren’t dismissed easily. Along with snoozing reminders, I guess.
Support for Google’s Inbox might be useful (by doing things within an email message), but I’m not sure just how yet.
Some people abhor Google, so if there’s a way to integrate CloudKit (and support for Apple Pay, I guess) so that way users could sign up through it, that might be reduce some and pay for itself. I have yet to see someone offer that, of course, so I’m not sure if it’s possible/viable/etc.
The search feature that @Yatharth_Agarwal suggested is a good idea.
Extensive settings, perhaps in a section for power users would be good, too.
“Special Dynalist Documents” that are automatically generated, containing reminders, bookmarks, and auto-update as new items are added would be nifty.
Cloned documents would be cool, too. Don’t know if that should be a pro-exclusive feature (and I’d hate to make users who suggested it who aren’t on the pro plan sad), but it could since people can technically link to other bullet points.
Perhaps a cap on how many people can work on a document? That might backfire, though.