Yes, but I had to try. C is still used in some applications, though most jobs don't use it. Consider how many people write the JVM, versus how many people just use it.
There will always be C/C++ jobs, but it's sort of a constant number of jobs that doesn't grow very fast. Embedded systems, mobile apps, OS work, games, and a few other domains need it. But in terms of getting a job it's certainly not the way to go.
I went out of my way to start making that my career because I enjoy systems-level work and had the resume to give me a fighting chance.
First: the CS degree is worth it. It isn't helpful on the job, but it gets you in the door lots of places, and there are companies who do actually care about that math. Do you need it: as I said, you don't. But it is a almost guaranteed path to a job.
Second: SQL is as strong as it's ever been. Postgres scales at least as far as MongoDB these days, and Google and Amazon have both bought into SQL for their big data offerings (Google BigQuery). Additionally cassandra exists and is used by at least Netflix and Apple, and scales to petabytes of data. And when I did the job search I interviewed with a company called MemSQL which is used by at least Comcast. There's also TiDB, which scales quite far and has at least one terabyte-scale client in China.
Uber uses MySQL for all of their ride tracking. I'm not sure where you got the idea that SQL doesn't scale for modern applications, other than perhaps that SQl Server itself has always been behind the curve. Modern Postgres is a superset of MongoDB with roughly the same performance: I have personally seen a single-node, non-sharded Postgres handle 10000 writes and 100000 reads a second, that setup probably scaled further but those are the numbers I can say with a straight face, and it definitely scales further than that if you start deploying it properly.
How this looks in practice is your permanent storage ends up being something like SQL, then you grab Redis for a cache, something like Rabbit for the job queue, etc. At the very largest scale yeah, you maybe use something else, but that usually ends up being a custom database specific to your company that your company developed for internal usage.
So, my point. The choice here is between learn SQL, which is used by at least 5 databases and has been around for literally 30 years while still going strong, and gets usage at companies of all sizes, from the smallest web site contractors to the big players like Uber, Netflix, and Apple, while also being used in almost every web framework ever. Or go learn today's database of the month because it "scales better" or whatever the claim is, only to have your knowledge be outdated in a couple years because rather than learn something good for your resume, you learned something specific to a small subset of problems that only the largest companies even have to care about in the first place.