If you mean the through sleeper to Penzance then yes, that still runs and the down train still seems to be booked to stand for almost an hour at Exeter, but it

If you mean the through sleeper to Penzance then yes, that still runs and the down train still seems to be booked to stand for almost an hour at Exeter, but it now departs around 4-ish, so quite a bit earlier. Going the other way it stays in the platform at Paddington for quite a while, so while it's booked to arrive shortly after 5:00, you can stay on until around 7-ish. One interesting thing I've seen in older timetables (late 70s / early 80s) is that in some intermediate locations (e.g. Carlisle) they apparently did the same thing with through carriages which were then shunted onto/off the main sleeper train in order to let passengers from that station board earlier/sleep longer than would be possible based on the arrival/departure times of the main portion of that train.