> How would Terraform help you move between cloud providers when all of the provisioners are specific to the cloud platform
You don't move. You load balance across the clouds prior to the disaster.
You have your stuff work on both. I mentioned K8s because you could set up a managed cluster of that on a few cloud providers, and most of your TF will be the same in terms of setting up k8s, with some differences on how you set up those clouds.
This might be overkill for many people though so see below...
> If you’re a small startup, the least of your business risks are one of the major cloud providers shutting down.
I agree. a major cloud provider wont shut down....
... but they might shut YOU down.
Why? Billing Issues / TOS / 'Suspicious Activity' [0] / etc.
Now do you mitigate for that? Not necessarily but it is worth considering if you need to.
At the preparedness extreme you have a probe that detects the problem and flicks you over to cloud 2. Or a load balancer as I mention above (which would probe). That's probably too much for a scrappy startup.
But a middle ground is you have tech that is easy to move. Doesn't have to be k8s/TF but maybe a bash script you run on a new debian VM or whatever. Then you phone one of you awesome developers at 3am and tell them to migrate to AWS or whatever, and because it's easy they'll figure it out as they go, most stuff running by 3:30am and everything dandy by 5am.
The other extreme is you are tied in heavily to specific stacks by specific providers, and it take X hours/days to get back online again.
I'm not recommending to anyone what to do here - but I am saying consider the black swan events. You might consider them and say no I want my devs adding feature X so we can sell more. Fine, but I think when you can spend $100k a month on cloud you can probably afford to think about it a bit.
[0] Source: one of the major cloud providers cut all our services for 12 hours due to "suspicious activity". Turned out later it was due to a reused IP we were given from a pool that someone else f'd with. They gave us some credits to be nice afterwards.