Re: beginning of the end
I'd wager the beginning of the end was probably close to a decade ago. Might of been when they did their initial big investment for OpenStack. Not that OpenStack was a bad idea at the time(had a lot of promise though to me promise has fallen flat the past 5-7 years mainly due to complexity), but it was a serious shift in technical strategy.
Couldn't find the article(think there is one) of when Rackspace was essentially pulling out of OpenStack.
I was never a customer of theirs but did price their stuff out on a couple occasions ~10 years ago the cost never made sense. Not that public cloud is any better(actually worse in many respects but some still eat it up because it's sexy I guess). Absolutely astonishing how much money is wasted in public cloud, just makes me sad.