#1 Potential introductions of Kenny Omega and/or Jim Ross
Jim Ross and Kenny Omega are both technically free from their contracts with New Japan Pro Wrestling.
While Omega is now a free agent, Ross is still technically under some sort of contractual obligation to WWE that might prevent him from being announced as the lead announcer for AEW.
Since he's likely out of the picture until his contract expires, the biggest 'surprise' that could show up in Las Vegas this Thursday would be in the form of one Kenny Omega. He's a free agent and some sources have already claimed that he is joining his friends in All Elite Wrestling.
While that all might be true, nothing is 100% true until we hear from the horse's mouth as to just where he'll be wrestling this year. He did say he was going to wrestle 'on a large, national platform', so where exactly would that mean?
NJPW is out since he didn't re-sign with the company. If he meant them, then he would have already announced that he'd re-upped with NJPW. Impact Wrestling and ROH are 'international' but not on the scale of WWE and potentially AEW. That means his choice will land with one or the other of the promotions.
Will he be revealed as the huge surprise guest on Thursday in Las Vegas? For some fans, the hope is yes while for those who want to see the Cleaner in WWE, the answer is no.