no
Because you have 3 slots that level independently of each other that you can switch between at a computer terminal in your house or in some location in the world.
Slot 1 ( Your default starting slot )
Level 8 : Soldier ( 2 ) Trader ( 0 ) Rogue ( 0 )
All Skills all base stats and leveling perks saved to Slot 1
Slot 2 ( Secondary )
Level 18 : Soldier ( 0 ) Trader ( 2 ) Rogue ( 1 )
All Skills all base stats and leveling perks saved to Slot 2
Slot 3 ( Third )
Level 28 : Soldier ( 0 ) Trader ( 0 ) Rogue ( 4 )
All Skills all base stats and leveling perks saved to Slot 3
So while your character can gain as many as 90 levels total the level cap for each slot is still 30.
The trick to this is that Once you pick up a new ability from leveling any one class to X level that ability becomes available to you at any point in time regardless of class or level.
So if I gain the "Berserk" ability for leveling a tier 2 soldier to X level then I will have berserk available as an ability for my level 1 slot 2 trader.
In many cases these abilities will not be as strong when used with the incorrect class some would end up being even stronger.
And the entire system would revolve around action points being a far more important resource.