Robertson has struggled mightily with injuries over his very short NHL career, but he does have a tremendous amount of skill and a relatively high ceiling. If he possesses even half of the skill and shooting ability that his brother Jason does in Dallas, Robertson could still be a very effective NHL player and a scoring threat. He remains a very intriguing piece and one that the Leafs may end up regretting moving if they do end up moving him. Having said that, you have to give something to get something and a move involving Ryan O'Reilly, who won a Stanley Cup and a Conn Smythe Trophy in 2019, is a pretty high profile deal and likely involves a top prospect like Robertson.
While the Leafs and Blues have not been linked in legitimate trade talks involving O'Reilly, there's still plenty of time between now and the March 3rd trade deadline for those talks to come to fruition.