I recently tried setting up another mining rig but found out all the profitable GPUs are no longer available at all local stores in my country. According to the distributors, people have been buying GPUs in BULK since April 2017.
At this rate, can GPU mining still be profitable long term? 1 year from now? 3 years from now?
No one knows...if some coins lose value or switch to PoS, you can move to another coin. From a business standpoint, if you are "in the black"; made your initial investment back and are turning a profit, no matter how small, you are doing okay.
There were some times, early on with bitcoin, when it was cheaper to buy coins on the market then to mine them...