It'll take more than a few years for anyone other than SpaceX, and perhaps Blue Origin, to start recovering entire boosters -- it's a lot harder than you might

It'll take more than a few years for anyone other than SpaceX, and perhaps Blue Origin, to start recovering entire boosters -- it's a lot harder than you might think to retrofit on an existing rocket, and those two companies are the only ones to have designed rockets from scratch for it (though Blue is ... ahem ... a little while yet from even starting to actually build their orbital launcher). Other launch providers are obviously watching, and the Indian space program, at least, is developing technology intended to feed into an eventual reusable design. But some of the others with announced plans still won't be trying to recover an intact stage, but only pieces, particularly the engines (detached in flight from the rest of the stage). That's the case both for Vulcan, the next-generation rocket from United Launch Alliance (the Pentagon's preferred provider), and for the Ariane-6 -- both of which won't initially launch with even that level of reuse, but only get it in follow-on work. (The reuse strategies for these are called SMART and Adeline, respectively, if you want to Google for them.)