Most people talk about some of the obvious problems Clash Royale has:
-That darn Cancel button
But one thing I am surprised isn't talking about more is the fact that a game like this goes both ways, if you want the game to be less stale and more fun to play then we have to help out by making our own decks instead of copy-pasting.
HONOR! A NEW CURRENCY!
You have probably gotten a quest once that told you to use a certain card like valkyrie in 1v1 arena battles or something similar, this idea is along the same lines as that.
To put it simply, the game will put a counter on every card, at the beginning of each day that cards counter goes down to zero (this is an individual counter for every player mind you.) This counter rises by 1 every time you use it in one day up to 10. If you get a card up to 5 you are rewarded a teeny bit of honor for using it, if you complete all 10 for a lot of different cards you gain a bit more out of it. Along with this I believe Supercell should severely nerf gold rewards in battles as well as the items in the card shop, so people will want to use this honor system to make up for the less gold.
This Honor is used in a new honor Shop which will go right under the card shop, in this Honor shop you trade Honor for rewards that are randomly put in this shop each day like the card shop, like the card shop it has 3 items to purchase and on Sunday it offers 6 items to purchase including an Honor value pack. But unlike the shop you don't buy just cards, you can buy gold, gems, cards, and maybe even emotes if supercell ever makes them obtainable for free. The items in this shop offer much more value than the what you would normally get just from grinding with the same deck, so you will benefit hugely just from using lots of different cards each day.
What I've written so far above won't fix anything on its own, people will just continue using Royale giant by simply combining it with different support cards than they usually use, thats why I believe a "staling" counter should be put on each card, so if you use a card and it reaches 10 uses in one day every use afterwards makes the card "stale" and you gaining negative honor for overusing it, this way people will have to stop using the same win-condition every time and will be forced to try something new and spice up the game.
This whole Concept I've created basically destroys the entire meta, but in my opinion thats a good thing. The Concept of meta cards and meta decks makes people want to use the same decks forever and it makes the game stale. Few people ever try anything new and spicy, this will make every battle different, because anyone who doesn't utilize the honor for its rewards are going to be really short on gold because of the crushed battle gold rewards.
Why Honor you ask? I thought it made sense because you were "Honoring" the cards by using them, paying them respect so to speak.