Yes, via event gacha (that means cash and card reveal)

Some cards return with every event gacha. However, some get marked as "limited" and those have now vanish from the gacha. The game is still very new, so I don't know if those previously limited cards will ever return or not.
I'm fairly certain that every card that has been obtained for free, aside from the event only cards, are still available. I have no idea if event cards are going to reappear or not.

So, i will never be able to have a full set of cards... thats a disappointment...

Don't play this game if that is your only goal. It won't happen unless you are willing to spend a fortune.

Are there any other goals? Everything in this game kinda revolves around collecting cards...

Throwing pie to others :v

Well, expect to spend money for former limited cards in the way. N ones however, turns down to N gacha passed some time (as happened with first elite guard event).

Oh, and event gacha doesn't ensure a limited card, this warning is from event gacha.

The box may be filled with some multiple and redudant SR cards

Originally Posted by Malzahar

Are there any other goals? Everything in this game kinda revolves around collecting cards...

There are/will be plenty you can collect. But the point is to have fun doing it. As long as you are enjoying the game, then it shouldn't matter if not every card is obtainable.

From what I've heard (from a person who got addicted to the JP version). They may at some point return, but it is all at the devs choice there is no guarantee.