I think there are a few notable things about Empoleon that contribute to its viability and high usage regardless of Pidgeot.
-it offers a lot of utility in one slot, so it works really well on balance or bulky offense teams which demand role compression. On one set it can do all of set hazards, remove hazards, spread status (Scald, though Toxic is viable if one other move isn't needed), and phase, while similar options like Tentacruel, Donphan, and Forretress have to pick and choose which of those they pack.
-with some investment in physical defense instead of the standard fully special spread, Empoleon becomes one of the better checks to Feraligatr (it can even run Grass Knot on such a set so that you aren't relying on a Scald burn to beat it)
-Empoleon isn't strictly limited to a defensive utility set; recently at least I've seen a lot of lure sets popping up with offensive spreads, particularly utilizing Shuca Berry to nab surprise kills on things like Aerodactyl, Nidoqueen, and even Mamoswine and Krookodile. Agility is also an option to really catch people off-guard and clean up weakened teams late game.
So maybe it was Pidgeot's presence that inspired people to experiment with Empoleon over similar options lately, but I don't see it falling to the wayside just because Pidge was banned.