phabricator:T5525#2152608 let us know that there is a watchlist survey ongoing, which reads «WMF's Community Tech team is working on a cross-wiki watchlist. This survey will help us understand how you use watchlists, so that we can create a cross-wiki watchlist that works for you. Thank you for participating!». Nemo 07:33, 26 March 2016 (UTC)
Contributions should indicate which are in watchlist
In Preferences, users will eventually discover
 Add pages and files I edit to my watchlist
They will say that is a great idea, and enable it.
But then they will say "what about all those pages I edited when it was unchecked? I wish Contributions had (solid) stars next to pages that are in my watchlist, so I can tell which of my Contributions aren't in my watchlist already (and perhaps even click on empty stars right there in Contributions to add them to my watchlist!)"
Better than cross-wiki watchlist...
Hi, cross-wiki watchlisting would be handy, putting all your lists into one... unless you have thousands of items on your watchlist...
What about also making a feature where you could create several watchlists. You could name and manage them yourself so that you've a watchlist for Wikipedia discussions, a watchlist for science, a watchlist for local topics etc, etc.. and then when you opened a watchlist not only would you feel able to check much more pages, but you'd be able to put yourself in a mental mode, focusing on a particular topic.