For me, the future of GPU mining depends on the market conditions, after all these cards do require quite a bit of power when mining crypto and you need to cover the electric bill. There is a GPU accelerator that is soon to enter the market that may make the efficiency of certain GPUs better.
There will be a big demand for GPU power in the crypto field for years to come, whether you can make a dime providing it, remains to be seen. Lets hope so!