I trust google to build good infrastructure more than I trust the collective developer community. That's one reason -- whatever they build will be more robust, flexible, and extensible. And immediately adopted by hundreds of millions of people automatically.
I guess that's not the same as "durable", but playing devil's advocate, those seem like good reasons to me.
The RSS system was partially so painful because it was so fragmented. Some pages had links to feeds, some used the proper meta tags, some just didn't have them because they lost control of the presentation of the content. Some were headline only, some were snippets, some were full-article. And every few months one of my feeds would change location so I'd have go set up the new feed. Sometimes they'd just go dark because their provider had an error and the blog author might not even know.
In short, the RSS system had lots of nice properties, but it just wasn't compelling, partially because it was so fragmented.
Google will generally make robust infrastructure that exists much longer than most small sites. I'm willing to put some trust in them, though I personally dislike G+.
The internet was built by a deceloper community collective... spread around the world in different universities... linux was built by another collective... and bittorrent... and apache....
have we forgotten that open distibuted systems are the most durable ones??
I guess that's not the same as "durable", but playing devil's advocate, those seem like good reasons to me.