I get the idea but I don't think it addresses the issue. There has to be a function that a) checks if instance exists b) checks if instance state is what I want (e.g. it has 8 GB ram) c) if not it updates the instance. Ideally it also locks environment while doing this to prevent race conditions. It can be written but seems to be quite cumbersome. Complexity of this code and also time it takes to run it what concerns me most.

I guess this is why terraform state is there. IMHO state is IaaC biggest weakness because you have to keep it consistent with actual cloud state. If we can just query state from the cloud and make it performant + be able to automatically (or just fast enough) select resources to be update it would be ideal.