Gail Kim ~ Sure, why not? From what I've seen of her in TNA (& to a lesser extent WWE), she was a really capable wrestler who was unfortunately around at a time where nobody even cared if you eliminated yourself from a battle royal. Having another talented wrestler in the female pool isn't an issue for me, even if she just returns to lose to Asuka in NXT.
Rob Van Dam ~ Rob Van Dam will probably be back in some form, I believe he said he's got a deal like Jericho with WWE but just isn't anywhere as motivated as Jericho. At this point I think RVD tackles wrestling with the passion of Brock Lesnar and he hates travel so I'm sure it wouldn't be too lengthy of a run, but despite him producing some terrible matches during his last run (I gave his bout with Del Rio at Night of Champions a 1/10 for reference) I still have a soft spot for RVD being an early all-time favorite of mine, so I wouldn't be totally opposed to another short, and I mean short, run.
Carlito ~ Yeah, Simon's idea of teaming him up with Primo & Epico (I recall being a pretty big fan of Carlito & Primo when they teamed) is pretty much what I'd want from him. He's a solid hand but I'm not going to lose any sleep if never returns nor am I interested in him doing much more than helping the tag division.
John Morrison ~ 100% yes. I should probably check out his work in Lucha Underground but I've always been a big fan of this guy, and I'll be happy with him returning assuming they'll give him some prominence.
Kharma ~ I'd be cool with this too. Not sure long term they'd be able to get much out of his but a feud with Nia Jax certainly has me intrigued. And it'd be nice if her WWE career had another match besides just the Royal Rumble.
Melina ~ So, I don't think I ever mentioned this before, but I'm a big fan of Melina. Like, I know if I'm associated with one diva/women-wrestler on here it's probably Eve Torres, seeing that I once hijacked an Eve Torres thread that lasted 9 god damn pages (Past me, ugh) and if you google image search "Mustafar Reginald" you'd still get a few pictures of Eve (also Ryback and Stephanie, which are pictures I did not post) but I actually consider Melina as perhaps my favorite women wrestler pre-Revolution. Not just because she once broke up a pinfall by screaming at the referee but because she managed to put on some really good bouts in her time. Like the Night of Champions bout with Michelle McCool that was so good they got reprimanded backstage for making the "guys look bad" until Jericho stood up for them because Jericho is awesome or the I Quit match with Beth, that had a pretty awesome bendy finish if nothing else. And she also had a more unique attire and a great entrance that at least allowed her a little personality. I'd like to see her return and I wouldn't even be opposed to another championship reign (especially since I assume she improved in the ring during her time away), much like how I wouldn't mind another Mickie James title reign (and she's why I prefaced Melina as "perhaps my favorite").
ECIII ~ He seems like a fine talent, I like his mic skills from what little I've seen of them but not convinced on his in-ring work. But I wouldn't take issue with him coming back, assuming they don't bring him back as Bateman.
MVP ~ It's probably not going to happen based on every interview I've seen from him (like the video mentions, but specifically with Chris Van Vilet [?] he stated he moved on comparing WWE to a hot girl that farts in her sleep) but MVP was one of the biggest reasons wrestling turned into a passion from me, as I quickly attached heavily to his feud with Kane so I would mark if he'd ever return to WWE.
Bobby Lashley ~ I was a Lashley fan during his original run, if he seriously only got better (which despite the first half of my comment, there was a lot to improve) then definitely yes. I'd especially enjoy to see a Lashley/Lesnar match-up, I wouldn't even mind if Bobby Lashley only returned for a short program with Lesnar, granted he's no Goldberg so I'm not sure how likely that option is but I'd be down for it.
Rey Mysterio ~ I would be fine with him having a run in the Cruiserweight division but not much past that.
Outside of those listed, Mr. Kennedy Kennedy is the wrestler I'd most want to return, for similar by magnified reasons as MVP. It's unlikely to happen but he impacted me as a wrestling fan, was solid in the ring, fantastic on the mic and has one of my favorite gimmicks still. Not to mention, his career is pretty disappointing, considering he came extremely close to winning the World Championship on two separate occasions but something got in the way each time at basically the last minute. Granted if he returned, which I don't think he will (he's stated they haven't reached out to him [for obvious reasons] and I believe he said he wouldn't want to deal with their schedule [think it had to do with wanting to be with his family]) but if he did I doubt his WWE world championship drought would be rectified. There's not really a top spot for him in the current landscape, despite my personal bias thinking their would.