I'd personally like to see Jynx get an evolution. It deserves one - Especially considering it's basically part of a trio with Electabuzz and Magmar. I really hope we see more evolutions for older Pokemon instead of Mega Evolutions. While I enjoy Mega Evolutions and the things they bring to the table, I feel like they should be reserved for second or third stage Pokemon that don't need any actual evolutions. I actually wouldn't even mind a generation or game with no new Pokemon, but instead - focuses on giving Pokemon more evolutions, that way they can get a few much needed Pokemon out of the way and THEN focus on more mega evolutions, or even focus on Mega Evolutions for those Evolutions.
I think Jynx's separation from Electabuzz and Magmar is probably because of the two version system, it's better for them to have duos instead of trios for version exclusivity purposes. So if Jynx is getting an evolution, it probably won't be because of Electabuzz and Magmar.
They were never a proper trio to begin with.
At most, they might have been supposed to be a trio while Red&Green were still in development, but even in that case, the idea was scrapped before release, because Jynx differs from the duo in too many ways.
As you can see, Jynx has a secondary type, has a lot weaker stats and differently distributed (whereas Electabuzz and Magmar feel like opposites), and instead of being a rare wild catch in an appropriate area, it's obtained through ingame trade.
You'd think that all 3 of them getting a pre-evolution in gen2 brought them closer than that, but actually, that's also when their genders don't match anymore for obvious reasons.
And even if one disregards the data and just wants to think of them as a group conceptually or thematically, or rather purely design-based... THAT fails spectacularly as well, as Magmar/Electabuzz are all about their element of Fire/Electric, which is plastered all over their bodies with obvious patterns. And while they do have a humanoid shape, they also have an animalistic side to them. Jynx on the other hand is a completely unique design.
You'd think that if they wanted to make a third member to Electabuzz/Magmar, it would be like a humanoid hare with a white/blue ice-pattern all over it.
Aaanyways... I have a feeling that if Jynx will get anything, it would be a Mega at this point.
But whether it would be a Mega or a regular evolution, one thing they could do is give it the Sylveon treatment. Getting Refrigerate, so its Hyper Voice becomes a double STAB boosted spread Ice move 8D