I think Toropchenko has the upside to be a good 2nd liner. Blais has a very tough road ahead of him - 26 goals or not. He's not a Ty Rattie, but it takes a lot more than not being a Ty Rattie for a guy of his pedigree, size, etc. to be a 2nd liner in the NHL. I see Blais as having a realistic upside of speedy 3rd liner that can score and not look awful on defense. Toropchenko might be more effective at the NHL level, imo. Blais is right there with him, though.
Toropchenko is by no means a poor skater, but he has more work to do to be truly effective up the lineup. His big body, skill, and tenacity make him at the very least a good net-front presence that can play big. If he can get his skating to above average, he could be a good power forward. I think he still needs to be better offensively (and I think he can), and he's no slouch defensively, either.
Blais is similar to Kyrou in that he is dynamic enough to be a top 6er, but if he can't stick on the top 6 due to his flaws outside of the offense, then he won't be as effective as a 3rd or 4th liner. Toropchenko has a higher floor, and a similar ceiling, imo.