This is the problem the original BattleForge had. The problem is not enough content. If you want to avoid this dame problem, make more content. Making the game more grind heavy by making pack aquisition take longer will bring you to much the same problem. Too much effort and not enough return for time invested.
Your problem with people obtaining cards is not by getting them in packs. It is via people purchasing the cards they want with BFP via the auction house. Therefor your problem is BFP generation. If people cannot obtain BFP that quickly, they cannot purchase cards more quickly.
As the people on discord "politely" i formed me, you can amass BFP at a staggering rate per week via the dailies alloting you 150 bfp a day and 1 pack that you sell to players for 400+ BFP. You can reduce the BFP gain by 3/4 if you simply disable selling packs to players. If thats something you dont want to do, then you can simply reduce the cost of buying packs from the game store from 450 BFP to something lower. The market will adjust, and you can lower everyone's BFP gain that way as selling a pack is 3/4 of a players BFP gain.
To answer your question as far as what do i do once i obtain all cards and upgrades, and charges. What i would do is experiment with different deck ideas in both pvp and pve.
The fun of battleforge (at least for me) is not only collecting cards, but deck building as well. Of course there is actually playing the game as well. Everything i love about a CCG AND an RTS. I understand not everyone will like every aspect, but that is no reason to ignore an aspect of the game.
As i tried to have a conversation in discord about this, (THAT YOU NEED TO GO READ :P) players will progress at the game at different speeds. You will have some players who have their 1 deck in mind and go about getting those specific cards immediately, you can consider these the hardcore players. And then you have the casuals who will crack packs, not sell the packs for bfp, and work with what cards they have. What i think the current consensus is, is that you are making the rules while only considering the hardcore players.
By doing this, you will drive away all the casuals. Admittedly on the converse, if you cater to only the casuals, you will drive away the hardcore. Find a happier medium.