But I don't think Disney has as much pressure to do it as Paramount might? I mean, this is really a cruise for kids, not adult nerds like us. From a percentage standpoint, ST has always had a more mature fan-base that would necessitate more "heavyweight" event content like a Shatner.
While I am sure kids would love to see Daisy Ridley or Harrison Ford, I submit that they will be just as content to see (masked) Kylo Ren, Chewbacca, Boba Fett, etc. - all non-face characters that can be performed cheaply by a CM. No egos, riders, entourages, appearance fees, agents, managers, schedule conflicts, etc.
Sansweet, Hidalgo, Tippett - they all come at a relative pittance, I imagine, and are - and I mean no disrespect to them when I say this - simply concessions to the SW nerd parents who want something to do on the cruise.