Go open source.
Going open souse would attract more attention to this project. It would also allow you to set up a system for other to contribute code for cards, this would allow new sets to be added much more quickly; again attracting more people to this project. Open source also protects this project from disappearing if you were to get a cease and desist(C&D), because everyone who works on cards and such would have a copy of the code, and could re-host it as a new thing so you would still be in compliance with the hypothetical C&D.
I think this is a great idea personally, axpendix (the owner of the site) does have it as a goal on his patreon here https://www.patreon.com/tcgone
The only problem is that the goal is set at 2000$ a month! I honestly don't see that happening at this moment with the player base being so small. Ironically I would believe if he set the goal much lower not only would it be achievable, he would make more money as more eyes would be on the project thanks to more people being able to work on it (for free cough cough) It's a good idea axpendix I'm telling you now. Hell I know it doesn't mean much but if you did open source it and got updated with all the newest sets I would donate every month.