Still good time to mine ?
It is almost allways good time to mine.
The unique moment when it is not, it is when the cost of the coin you mine is less than the price of your electricity. Then, you will prefer to buy the coin and not mining it.

What will happen if there are no more GPU in the market?
This will be a very good opportunity for the miners : the difficulty stop to grows and it's make more time to redeem the GPUs