There are only a few makers of bow thrusters, and AFAIK none of the main ones have gone out of business in the last few decades. It shouldn't be difficult to find a like for like replacement.
But what is "end of life"? Electric
tunnel thrusters have two main components -- the motor
, and the drive leg. The motors should last virtually forever, in the worst case maybe needing some bearings and brushes
. The drive legs need replacement from time to time when sea water
gets into the gearbox
-- don't ask me how I know. AFAIK, replacement drive legs are available for all of the old Sleipner ones -- I had no problem finding one for mine, although mine is an obsolete model (10HP). For Vetus etc. I don't know, but I bet the situation is the same.