Worst Case Scenario
 

I took the DLAB to humour my recruiter, and got a 124. I felt pressured to relcass to CTI from IC (a rate I was kind of excited for), and now I'm not 100% confident that I will succeed at the DLI, especially since I qualified for Cat IV languages and can only attribute that to test-taking skills, not language aptitude skills.
In the worst case scenario that I fail out of the DLI, what will happen? Will I be put in a lower level language, or will I reclass into whatever has an open spot? Would I get any say, in that case? I've also heard from some people that I would be considered undesignated and sent into the fleet to do grunt work.
Does anyone know (from experience of otherwise) what would actually happen?
I'm not really planning on failing, I'll work hard to make sure I don't, but I really don't feel I can learn a language/culture/etc fluently in a year and a half.

You'll be assigned another rate. It's impossible to tell you what the rate will be because it's based on what's available at the time. I was dropped from CTN and was given three options that I had to compete with another sailor for. But while I was at Corry Station I met three different folks that were re-rated from CTI (2 to CTR and 1 to CTN). All three were dropped from Korean. Worst case scenario you get re-rated to PACT seaman. Not likely though unless you specifically choose that route. You'd most likely get a choice of three to five options to choose from.

Thank you for answering! I was a little worried, but any CT rate would interest me, although I wouldn't mind too much if an IC rate was offered to me again

In most cases, only Lack of Effort drops will be sent undes. I've seen cases where LOAs went undes, but very rarely and only when there were no other openings for them.

I have seen relanguages, but they're also fairly rare. Most people will get a new rating, and I'd say about half stay CTs - I know DLI drops who are now CTTs, CTRs, CTNs, and CTMs.

I also met people who went MA, LS, AD, Seabee (not sure which rating) etc etc. If you're a good Sailor, leadership will go to bat to get you a rate you'll like.

Having said all this, going in expecting to fail is the wrong attitude to have about DLI because it'll be a self-fulfilling prophecy. A 124 is a good score. Testing skills are important to CTIs. You know what we do at DLI? Lots of tests. You know how we measure our proficiency in our languages? DLPTs, which for most languages are multiple choice tests. Don't worry about "fluency", because a) that's not what DLI does and b) there's no consensus on what the word even means as applied to linguists.