I think both the capital S Semantic Web and the lowercase semantic web (microformats) kind of just fizzled out towards the end of last decade without changing much at all on the actual web.

The lower case variety kind of survives as a smart thing to do to "help" search engines a little but otherwise has very little real world relevance. All talk of doing anything with on page information in browsers evaporated a long time ago. E.g. MS had some plans with this with early versions of Edge and there were some nice extensions for Chrome and Firefox as well. Not a thing any more. Most of that got unceremoniously ripped out of browsers a long time ago. At this point it's basically just good SEO practice to use microformats as search engines can use all the help they need to figure out what is what on a page. Other than that, whether you render your data to a canvas, a table, or nice semantic HTML has very little relevance for anyone. It's all just pixels that hit your eyeballs in the end. There's nothing else that looks at that information. With the exception of search engines. And they were part of web 1.0 already.

The capital S Semantic Web with ontologies, triple databases, etc. never really got out of the gates and is perpetually stuck in people doing very academic stuff or specialist niche stuff that largely does not matter to anyone else. The exception is graph databases, which are still used in some data/backend teams for some stuff. And of course a few of those also pay lip service to some of the Semantic Web W3C standards from the early 2000s even though that is not the main thing they do anymore. Either way, too much of a specialist thing to call it a semantic web (capital or lower case). Most of the web uses exactly none of this stuff. But nice tools to have if you need them. You could argue a lot of the people involved moved their focus to AI and machine learning, which certainly looks like it is having a very large impact on e.g. search engines.

I guess web3 has that in common with web 3.0 (other than the number 3). There are a few people who desperately (and loudly) want the web to go their way and insist it must be the future. But most people couldn't care less. In the end people just vote with their feet and gravitate to technologies that work for them or solve a problem they have and ignore things that don't do anything useful for them. In the case of Semantic Web, there was nothing there that you could coherently explain (i.e. without using all sorts of abstractions, complex stuff, and simplistic hyperbole). There were a few startups and lots of hype. They did a bunch of stuff. Most of those startups no longer exist or have faded into irrelevance. And the few that survived carved out a few interesting niches but did not end up producing any mainstream, must have technology. Certainly no unicorns there. Wolfram Alpha probably is one of the more well-known ones that actually shipped something useful. But it's a destination and not the web.

Web3 has the same issues. Most threads on HN on web3 devolve into people talking about what it is, ought to be, or isn't and why that is or isn't important. That seems to be impossible to do without using a lot of hyperbole and BS. Very little substance in terms of widely adopted technology or even in terms of what that technology looks like or should look like. It's Web 1.0 all over again. Step 1 Blockchain, Step 2: ????, Step 3: Profit (or not).

Most of the web is just a slightly slicker version of what we had 15 years ago (web 2.0). AJAX definitely became common place. We now have mature versions of HTML, SVG, CSS, etc. that actually work. And with WASM we can finally engineer some proper software without having to worry about polyfills and other crazy hacks to make javascript do stuff it clearly is not very good at. I'm looking forward to the next 15 years. It's going to be interesting and possibly a wild ride.