If McDavid plays out his deal and signs in free agency, I'd say the Sharks are a lot closer to contending than 5 years.
Seriously though if I'm McDavid I'd give Edmonton one more go this year (what a disaster that will be) and sign as a UFA in San Jose. Surrounding yourself with Smith, Celebrini, Misa, Eklund, Dickenson and Askarov would be unlike anything he's had in Edmonton all this time.