The Gloaming
23
Strength and speed aren't mutually exclusive. McDavid will get stronger, but it doesn't mean it will affect his speed. For starters, the majority of McDavid's speed comes from his incredible footwork, genetics and skating technique, not from freakish fitness scores. Additionally, I'd hope the best player in the world is getting his training advice from people who actually know what they're talking about and who are creating a plan focused around training for power, while implementing translatable training to the ice. Needless to say I'm really not concerned. No training is going to take away his genetics and motor trained ability to skate like that.
Seriously, he was skating like this at 13. This kind of skating stride will be with him until he retires.