In tax loss selling, I believe you are looking to realize a loss to offset a gain in another transaction. So, this could be a factor this year with many stocks up five fold or more if you were smart and lucky in your timing and stock selection.
One of the biggest gains I have seen is domtar... UFS. a buck and a half in the spring, $55 now. No, I don't own it! Would have to sell a lot of losing stocks to offset an investment in that!