I don't see why not.
It may seem like just yesterday when he scored his first NHL goal against the Red Wings, but by the end of the season, he'll have played nearly 400 games in a Maple Leafs uniform. There's a clearly a level of comfort he has with this franchise and with the City.
I don't think its between Pittsburgh versus Toronto. If the offers are remotely similar, I'd expect Kulemin to stay in Toronto. Maybe he can even convince Malkin to join him, instead of the other way around.
The KHL will be the wildcard. A lot of people will dismiss the KHL, overlooking their obvious business strategy: They aren't interested in getting Canadians or Americans or even Swedes there from the NHL, they're interested in Russians and those from the former Soviet bloc. It is a lot easier to get someone who speaks the language and is familiar with the culture, especially if you overpay, then it is to convince others. And there's enough players of that background where you can have a very competitive league, arguably the second best in the world, and getting better.
For that reason, I think there is some reason to worry, though no reason to look at it as a foregone conclusion. Kulemin regularly plays for the Russian National Team, making him an attractive target for KHL teams. He also produced near a point-per-game in his lockout stint, meaning they could pay more because they're paying for an offensive player and we'd be paying for a defensive one. In the end, its all up to Kulemin. We can only offer him $3-3.5 million, unless his production picks up again. He could probably get close to $5 million in the KHL.