I think the point is kinda being missed here. There will be no shield skills, period. Gladiator may gain a few of the abilities that currently belong to shield, but there will only be 15 gladiator abilities at level 50, so I can't see those shield skills making the cut unless they are very beneficial to the Gladiator's role. Even if Gladiator inherits every ability from shield, it's still not a shield ability. It will be a gladiator ability.
You can argue that you should get a return on your investment in leveling shield, but very few people specifically leveled shield. It's always been a silly tacked on class, and it levels as you level another class. Very few people leveled shield. Most people ended up with shield leveled as a side effect.
Every class will be losing some skills that are situationally useful. If you are worried about losing out on abilities that you currently possess, then Shield is probably the least of your concerns.