Experience after level 30 counted towards new level system?

Rito just posted something about how there won't be a level 30 cap anymore.

My question is this, suppose someone has played since season 2, now he's going to accumulate A LOT of "phantom XP" after he reaches level 30. Now, here is another person who has just reached level 30 and therefore won't have that much as the player listed formerly.

Will both players start at level 30 and have identical experience after the patch? Or will the player who have played since season 2 going to get a head start?

Thank you for your time.