Microsoft leaves Access out of many of its Office license plans, so it's an extra cost add-on to most people, hence uninteresting.
Filemaker is very nice, but even more costly in most cases.
I've never used Base in LibreOffice, but I also don't see people sharing their Base files, from which I infer that it isn't very popular. (Could be my myopia, though.)
Even if LibreOffice Base is gaining users much more rapidly than I think it is, they're missing the cloud component for offline and mobile users, which acts as a brake on adoption, given Office365 and Google Sheets pushing people to stick with spreadsheets when they want to share tabular data across sites and to mobile users.
Collabora Online is moving LibreOffice into the cloud, but they haven't done anything with Base, as far as I can see.
Apple's iWork web apps are very nice, and they have native clients on many of the platforms I care about, but there's no GUI database component at all.
Without a free, cloud-capable, normal-person focused GUI/web database system, I don't see Excel-as-database going away.