While the RPC was subsumed into the RLC in 93, the pioneer trade continued at 23 Pioneer Regt RLC and 168 Pioneer Regt RLC until 2014. ARRC Sp Bn at Imjin Bks also had many pioneers.
I don't know if the pioneer regiments' disbandment simply meant the remaining pioneers were made redundant, or whether they were allowed to serve out their engagements on other duties.
From experience, they were not the sharpest tools in the shed, but would give you the shirt off their backs. I enjoyed serving with them (HQ ARRC).