I think it depends if what GPU are you using if you have only low specs of GPU you can only earn cents per day.. now many people are mining ethereum so the rewards is decreasing and many people are buying more effective and high performance GPU and increase the GPU in there mining rig..
So if you have more GPU mining its still profitable..
That is right. If you have the old GPU like the 7970, the efficiency is low, it will become less profitable soon.
If it is RX480, it is more profitable.
if you want to buy new GPU, it will cost even more dollars. Reinvest for ETH mining is not that much worthy. At least old gpu will mine something without any investment.