TL;DR: My suggestion for every Domino/Notes developer is to run away!
First time I was planning to "abandon" Domino as my primary application platform around 2002, when I decided to switch to Java. A decision that has proven to be very wise during last 14 years. First of all learning how things are done elsewhere helped me to get better at developing programs in general. And it helped me to recognize what were weak points of Domino/Notes platform, what were its strong ones and when to use it and when don't. But I did not leave, Domino and Java were taking approximately half of my time each.
Second time I was planning to leave around the time XPages were introduced. And it has stopped me from doing so. It showed me the potential of the platform that (with right approach and focus from IBM) could have been really successful. In my opinion, at least. I really did believe in it, silly me :-)
Third time is now. I don't think there is anything left to be done, even if IBM wanted to (and they do not want or can not). It is just too late. People still can make good money maintaining existing apps and maybe adding web interfaces to them. But they are facing the same fate as Cobol programmers. Still couple of them work on ancient applications as you read this, they probably make good money, but there is no future for them.
If you do just Domino/Notes, maybe not even XPages, not even Java in Domino, you are in a serious trouble. Without moving on and learning new modern stuff, your position on the market is hopeless. Unless you have two years to retirement age and a nice job at company with a lot of Notes apps.
There are still millions of Notes application being used. I wonder what suggestion will IBM make to customers as to where to migrate them etc. I would not be surprised by IBM providing services to aid the migration to some other vendor's platform. They are still making a lot of money for renewal of existing licences and I guess they will try to make as much money as possible. Sadly, in expense of customers, in expense of loyal business partners (I would be very happy to be proven wrong on this).