It’s about 5 times longer than previous releases were maintained for, and is an experiment. If there’s a need for a longer term support branch, there will be one. It’s pointless to start maintaining an 5+ year branch with 0 users and a handful of volunteers, none of whom are paid for doing the maintenance.
So yes, in that context, 15 months is long.
I don’t use the builtin bookmarks. I use Readeck (and Wallabag before it) to save stuff for later. Lets me tag them, has good search, and even archives what I save. Comfortable to use on phone, too.
Does require selfhosting it, though.