If we look at the likes of Unity3D, nothing was perfect straight off the bat, and I feel like the same can be said of Serverless architectures.

The people offering serverless are no doubt aware of the difficulties and I wouldn't be surprised if they said they were developing something that would make this easier.

Cold starts are a valid issue though and I feel that the effects of this can be minimized with the use of fast compiled languages such as Go.

Lock-in is also a worry for most, as we progress we need to ensure that we are able to write serverless code in such a manner that they can easily be transported across to other serverless providers.