HTML/HTTP may some day be obsolete, but will likely be around longer than anything built on complicated javascript frameworks or tightly tied to current web browser technologies.
Otherwise, some setup using S3-as-a-website or GitHub pages may work, but those also depend on the company maintaining that service.
If your entire website can be dropped into a ZIP file and served anywhere, you have a greater chance in it surviving, especially if the internet archive got a copy at some point.
But if you die and nobody cares about the content, eventually it will disappear.
Well, your entire website can be a zip: https://redbean.dev/
Frameworks and Browsers change. External services change. But, unless its stored with no backup and the medium fails, an ASCII textfile composed 50 years ago is still readable today, and will likely still be readable in 100 years. And thanks to UTF-8 being pretty much ubiquitous these days, we don't even have to limit ourselves to ASCII any more.
I am not saying to make every page a textfile. I am merely saying that one step to preserve digital information for generations yet to come, is to represent it in simple and robust formats. And if simple is not an option (eg. media will probably need to be use a compression format), then well documented and open formats should be used.
There's no obligation for a person to maintain anything longer than he wants to do it. Putting a blog online is not a lifetime committment. Interests change, or you simply realize nobody much cares about your online musings, and you move on to other interests.