I have not really been keeping up to date with all the changes... With a game of this type though, new players need to keep joining and buying the new cards they are creating.
They need to create some sort of battle mechanic with the land feature that allows you to create armies you can attack other players with. The more cards you have the bigger the army you can create to kill other players.
It is difficult, because the people who have lots of cards have to be rewarded for owning a lot of cards, but at the same time you want new players to join and still be able to compete...
I like your idea with the battle mechanics (actually starting with Rebellion). But I think they should implement the mechanics with existing cards, instead of constantly flooding the game with new cards...I know that Splinterlands the company needs some kind of revenue, but there has to be other ways obtaining that...and yes, it's difficult to make something that is fair for everyone, but I hate the fact that people with older cards are not able to compete, because newer cards have more abilities...