My bet is that you only chance is making it a family history site. And by that I mean that each generation of your future family must contribute their story and at the same time update the site to a modern solution.
The base layer could be text files and image, even though jpeg might not exists in 200 year some other format does.
But you must leave it up to you grandchildren to update the solution to modern formats. Maybe set some inheritance up to support this.
Or use a free family history site (https://familysearch.org ) maintained by a church/religion with a track record, size/growth, and that has realistic expectation to be around for the long haul. Details in my longer comment in this discussion. :)
I actually love this idea. A digital version of the family bible. Which had the alternate purpose of stewarding the family lineage through generations. Sans the religious bit.
The base layer could be text files and image, even though jpeg might not exists in 200 year some other format does.
But you must leave it up to you grandchildren to update the solution to modern formats. Maybe set some inheritance up to support this.