Sure, you could use multiple clouds for a couple of small things, but it's all about the data.

To properly do multi-cloud (or hybrid cloud), you need to have the right data in the right place at the right time, or you need to have all your data in both places at all times.

The latter will cost you a fortune to maintain. Netflix does it across regions because their cost of operations, including keeping multiple copies of all the data, is lower than the cost of downtime, but that isn't likely to apply to most people.

The former can only work if you are really disciplined about keeping the right data in the right place, or if you have a data abstraction layer that is smart enough to put the right data in the right place at the right time (I'm not aware of the existence of such a product or that anyone is even working on such a thing).

The other problem with multi-cloud is that your software has to be built to the lowest common denominator. In other words, you can only use features that all your providers provide, again unless you go back to having software smart enough to do the right thing in the right place at the right time.

It's a nice thought but I think we're years away from viable multi-cloud.