The only significant effect of this episode was to establish a Warp 5 limit for all starships, but even that was forgotten after TNG ended.
They could have worked with that, though. The main other ships post-TNG were:
* The runabouts on DS9, which I think only went W5 or so anyway.
* The shuttles, which went W4.
* Voyager. All they had to do was this, in "Caretaker".
TOM: "Those look like retractable nacelles."
STADI: "Yes. Voyager uses a variable geometry warp field, which doesn't adversely affect subspace the way a conventional warp field does."
* The Defiant. Just explain that it's a small ship with internalized nacelles, and its warp field already has a subspace-safe geometry, or it has a negligible subspace footprint, or just have O'Brien announce that he's completed the modifications on the drive that will allow it to safely exceed warp speed limits.
First rule of Trek: technobabble resolves everything. But you have to at least make the effort.
Once all that's done, simply never mention the warp 5 speed limit again.
*~*~*
"Thine Own Self" highlights one of Trek's most ludicrous comparisons...
DATA: Saves Earth from the Borg. Saves the Federation by ending the Klingon civil war. Still a freaking lieutenant commander.
TROI: Requires multiple attempts to kill a hologram of Geordi LaForge. Promoted to CDR. Data has to call her "sir".