He hasn't dominated in Liiga yet. Let him first do that.
Then he'll move to the NHL, try to challenge for a spot at the training camp next year and skip the AHL if he's ready or start the year in the AHL and then take over more slowly.
And he can join Texas in the upcoming season if they make it to the playoffs IF he isn't too busy with the international games etc.
How about that Heiskanen plays 9 NHL games to Dallas this season and after that he returns to HIFK.
That would make it possible Heiskanen's ELC contract will move forward for one year and makes him calder trophy eligible for season 2018-2019.
I don't know exactly how many international games Heiskanen plays this season ( 2017-2018).
World juniors in Buffalo are of course one tournament where Heiskanen participates for sure if he isn't full-time NHLer.
2018 Winter Olympic games in South Korea are a month after world juniors so it's unlikely to see Heiskanen there.
But 2018 IIHF hockey world championships in Denmark is that tournament where Heiskanen could be in Finland's team.
Of course that depends a lot of that how many NHL and KHL players Finland will get that tournament.
If Heiskanen makes it and plays to NHL whole season then he'll miss world juniors in Buffalo.
But Dallas Stars legend Jere Lehtinen is now Finland's national team GM so maybe Jere can talk to Nill and get Heiskanen released to world juniors.
Or hockey world championships in Denmark if Heiskanen really plays to NHL this season.