Will it matter to YOU in 3 years.
1) you still get paid.
2) you still get rated for promotion.
So no, it will not matter, to YOU, in 3 years.
But if your ratings for promotion are based on your lack of productivity in the "boring product" that is "using old tech", and you have enumerated the problems to management . . .
In otherwords, if management has taken their problem and made it your problem . . .
Then the answer is clear: it's time to move on.
personally, for me, life and job satisfaction is above promotions. 3 years of doing what I don't like, without any passion or interest, and getting skills that will not matter (and this is not a good thing) isn't good, neither for me, nor for my career.
when I pondered on these questions a couple of years ago, I decided that it matters, and changed my job as soon as possible. Life is too short.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.