Geras is sub-boss for this one (per Shaun Himmerick), unless there's 2 sub-bosses in MK11.
I'm also thinking like you [MENTION=18134]Yellow Ledbetter[/MENTION] that maybe Raiden did mess with the Dragon King's plans.
If Reptile's not playable in MK11, then I'm thinking that maaaaaaaaybe it could be a reference to Onaga, given that Reptile's body was used as the host for Onaga in the old timeline.
Argh! I need some of the answers to these questions.
Like, now that Geras and Kronika are confirmed, does this also mean that there is an anti-Geras / Kronika new MK11 character, as rumored, who maybe DOES agree with Raiden and / or disagrees with Kronika?
Well, those old leaks - the ones that didn't mention Skarlet but did mention Kronika and Geras (even Ronda) by name - stated that Geras would be at odds with Kronika. I believe that leak is legit, but it was possibly from an early draft. But who knows right?
I think Geras being a sub boss is a little "meh", except if he's Shang Tsung MKII style. I wouldn't mind seeing Onaga as sub-boss, even though I always wanted him to return as big bad.
About Raiden messing with the Dragon King's plan, I think two ways: either Raiden did by accident sending Cassie, or he was already Dark Raiden (we can't see his eyes on that ending) and sent Cassie knowing Shujinko was innocent, since he had visions of Onaga in MK9.
Anyway, Deception timeline was confusing, and we don't know the equivalent time compared to MKX. Sonya and Cage could absolutely be at their 50s during Deception, but graphics couldn't tell, and they only mentioned in MK

A that Earthrealm has enjoyed relative peace
for many years. So, the return of the Dragon King could totally be delayed if Cassie indeed killed Shujinko and that fight happened in what would be the time Shujinko would do something relevant for his return.
Also, Edenia wasn't freed due Raiden's changes, but I think Onaga would only need Outworld's Kamidogu. The Amulet also stood under Raiden's protection for a long time.
That raises an interesting question then: when MKX was set when comparing the unchanged timeline? I don't think nobody has this answer.