I'm self-taught as well, and I'd say look through the current job market and offerings, but don't worry all that much - teaching yourself IT usually nets you a considerable amount of transferable skills that you build upon if things don't work out in one field; you also learn to learn and get much more comfortable with switching branches.

The less volatile your branch is, the less likely it is to turn out to be a fad that you'll have to drop several years down the line at best. Crypto and blockchain, for example, were probably often recommended when the thing was on the rise, but that's nowhere near as popular and safe now; I believe the current AI hype to follow the same fate. Basically, look at the news and trends and be careful with whatever big and stupid corporations push for, praise, or massively invest in: that's usually nothing but good marketing successfully baiting the suits.

Web develoment is probably going to stay simultaneously volatile and relevant for decades more, so that's a good option. Embedded development shouldn't be going anywhere either, although that's more low-level and intimidating, but it can be fun and stable and pay relatively well. I hate the smartphones industry and can't really say much about Android or iOS development, but I doubt it's doomed or anything.

So far, it seems like not following whatever Elon Musk or other billionaires tell you is the future is a good bet.