I've heard this burst-to-cloud story for many years now - Paul Maritz pitched it heavily as the pillar of VMware's value/strategy when he took over there.

I've yet to ever see or hear of it properly executed in practice. I think it's a really hard thing to try and bolt on to a legacy system, and if you build a new ground-up app this way going full cloud to start is easy and cheap for a while until you're successful and then the economics are.. complex.

I think there's also the weird angle to it that the folks who have the skill to architect apps like this are very hard to come by.

Would love to be proven wrong and hear about folks who've seen burst-to-cloud work out in practice though!