They've clearly spent the last 10 years spending like crazy, in a frantic (and successful) effort to diversify their offerings.
Yes, they'll first and foremost be "internet walmart", but only a fool would think that the insane growth was unstoppable - Jeff Bezos is many things but he's not an idiot.
Decentralize means a lot and has a lot of impact. It's not as easy as "installing the blockchain".
Instead, it might be more fruitful to take regular archives of it. Indeed, that is a supported action (wikipedia is intently copyleft) and many people already do it.
Lock-in sucks, but it's real.