Overall they just need more ways to win coins. Bring things like 2 player skill games where the winner takes coins, challenges against CPU or real person, something like first to score a headed goal gets 2000 coins. There's so much potential for online versus that could be really fun and not limited to just matches.
Or even set achievements that get you coins that aren't necessarily challenges. Stuff like scoring an overhead kick, or scoring from 40 yards out. The achievement could only get you coins the once otherwise it'd ruin the game with people taking long shots and always trying to do shit to get coins. But they could have 100k FIFA 16 Coins PS3.
I like the OP's higher rewards for seasons, but the idea of challenges against your friends would be great. Skill games might cause coin hungry people to only play skill games, but in game challenges would be great if they set them up similarly to BF4 (set number of matches to achieve some basic achievement like 10 goals or 3 clean sheets)
Prices of players will be significantly lower in many cases, the economy is just so fucked up from all the bots they had to set it as it is. But I agree with a reward system that actually rewards you for playing the game, especially the different seasons from different leagues someone else mentioned. It would bring so much variety to the online aspect of the game without ANY WORK AT ALL (since the concept is already in game).
People thought prices would revert back to FUT 12-esque at the beginning of this year when EA had promised to be strict on coinselling(haha remember that?), well it obviously didn't happen. But if the price band carries over to FIFA 16, where FIFA 16 Coins PS4 generating bots become extinct, and given they don't come back at all, it is very reasonable to expect lower prices across the board for the next game.