I generally suck at fifa19 but I like the concept of the game and think it is well done.
However, there are few things I hope will be addressed in the future
1) stadium: I think those cards should be boosted a little as they are not worth much and I mostly quick sell them. I would suggest to earn coins for the stadium you have based on which league you are playing in and your results. In brief, the more you win, the more people comes to the stadium, the more coins you earn. Bigger and fancier stadium will be more profitable than smaller ones. In this way also the cards will acquire values.
2) Trainers: as far as I understand they are used mainly for chemistry purpose. I would suggest that they boost some feature of the team. For example, Allegri can boost defense, Guardiola would boost tiki taka and so on. In this way also the cards will acquire value and different teams can boost different features playing in a slightly different way. Nowadays the vast majority of people play high press, ultra attacking. Then you would put Allegri card for example and contrast them better.
3) it is very boring to see the same teams all the time. This is not even so much reflecting reality. I would suggest to make cards of each player with a special edition that gives you 2 points of chemistry boost so you can actually have your premier league striker together with your la liga team. Those cards would be more expensive.
4) collectables: soooooo boring. They are mostly quick sell. I would suggest to do sbc with those which would give you special items you could not have in any other way. For example, a special song in the stadium during matches, pack with consumables, coins and so on.
5) please limit the possibility to buy the same player over and over. I do understand that many people profit on that. So, I would not say to remove it but limit it. I believe that coins should be made by both playing the game and using the market, not abusing it. 3-4 players of the same kind will limit market manipulation and abuse.
6. What do you think if cards would gain or lose values according to the player performance? For example, not every Ronaldo 94 will be the same. It depends who has used those and the how he/she performed.
What do you think? Other ideas to make the game better?