This game doesn't have a bright future to be honest if Konami doesn't do anything major fast. The grindy gameplay of this game is pretty one-dimensional, speed duel is very limited to what you can do with it, especially with such a small card pool and if some of the stronger cards get added the game will crash.

The game won't reach pogo' fate, ever, by that I mean it won't reach the mainstream and won't generate millions and millions despite droppping heavily in popularity. Pogo appeals to a much wider audience and like it or not, the game has some interesting social benefits that is highly attractive. Niantic is dealing with their issues slowly and by gen4 the game will most likely get more popular again.

Meanwhile how do you see this game in the future? Xyz? Pendulum? Unattractive characters no one knows? Cards from Duel Monsters that will make gameplay highly unrewarding for 20 cards? Pay to get those cards which means even more pay2win? Or grind the hell out of all those new characters and waste hundreds of hours just to "enjoy" 10% of them (through pvp..etc)?

It's a matter of time until people realize this is a waste of time and money.