The term is subjective. Don't see how you can make one definition the standard for "Blue Chip". There's not a lot of qualifiers that are set in stone, each draft year the goal posts move because each member of a draft class is rated relative to each other and the year before. PPG is probably still the best indicator but it is not without its flaws either.
If the consensus is that there is a high probability(>70%) that the prospect will become a significant contributor on an NHL team, then the prospect has garnered enough attention to earn the "Blue Chip" signifier in my eyes.
Jankowski is probably the closest on that prospect list, and a case could be made for him if you just take his AHL season. Considering the whole body of work however, he still has some question marks.