Driftjack will probably return in the opening story. They need a new Autobot to fill up Optimus' place
As far as Wheeljack is most likely going to be the team inventor able to oimprovise in the field and invent in the lab. Who thinks that wheeljack brings along Grimlock who in this incarnation is an intelligent and very capable leader who has a damage vocal processor that was a result from Shockwave's experiment that caused Grimlock to transform into a robotic Tyrannosaurus Rex. This incarnation Grimlock would be the most suitable replacement leader, although team Prime will not like it.
I Hope the first episode of season 2 starts off with new members but given we went a whole season with no permanent additions to the cast I'm worried they're going to drag out the first few episodes with the same cast and introduce new characters later on both sides. Fingers crossed Wheeljack is back at the start and we get a new Autobot companion with him and both are permanent additions.
Rumor is that we're getting Wheeljack as a permanent member in S2 and two more new guys, but one of Team Prime bites it to make way.
^^Yeah at this rate I think Wheeljack may be a permanate cast member. Though I strongly think Bulkhead will be the one to bite it. Hopefully Prowl and/or Jazz may be thr other two. Maybe even Grimlock may be a member though that's highly unlikey seeing how he's the leader of his own team.
My ideal Season 2 cast would be: Ratchet (as a hesitant fill-in for Prime) Arcee Bumblebee Wheeljack Elita (as a relatively small sports car) Ironhide (as a pick-up truck) Bulkhead would die by Bruticus Maximus' hand a couple of episodes in, marking Starscream's return with the Combaticons. This would make Miko grow up and quit having such a "throw caution to the wind" attitude about the war because Bulkhead died saving her.
Nah, I'd rather see Jazz and Perceptor. Elita needs to be a graceful but large vehicle, with around the same mass as Prime. So, maybe a European semi-cab? But Ironhide would be neat to see.
Perceptor would be great to see as well. He could possibly help Ratchet out with the synthetic energon formula. But I don't know about Elita being as big as Prime. Not even Bulkhead is as big as him, and he's enormous. Now that I think about it, a good size for her would be about Ratchet's height. Jazz = awesome, no doubt about it. However, I think he would be better as a cameo in a flashback near the end of S2 and a core character in Season 3.
I would like to see if Grimlock takes the mantle of leadership for Team Prime for a while. I mean he's more of a realest than Optimus and he may take it to prove Primes leadership is wrong. Of course he may go overboard which will cause tension with the rest of the team. Though if Bulkhead dies will Wheeljack go on a revenge spree? They are best buds with each other but Wheeljack is more of the mellow type it seems,or maybe it's a facade....
The return of Wheeljack will be great to see. I would hate to see Bulkhead gone as I have grown attached to him, but if it brings in more Bots, I'm down. I'd love to see Ironhide and Jazz and Sideswipe.
I think Ratchet will be the leader for a small while giving it too Arcee eventually and Wheeljack returns to be the Groundbridge operator.
I don't care as long as he brings in some re-enforcements. If it was up to me It'd be either Ultra Magnus, Perceptor, Prowl, Rodimus, Grimlock or a and maybe a little flyer some one like Breakaway.
If they bring in a flyer, it's likely going to be an "Aerialbot" so like Silverbolt, Air Raid or Jetfire (I think he was considered one).
I hope he returns at some point prior to episode 8 (the S1 episode he premiered in). Becomes a permanent member of the cast, as well as returning with another Wrecker. Because the creators have stated that he IS an inventor/mechanic like G1 Wheeljack. That side of him was just something that we weren't able to see in his debut episode.