Take a look at this thread if you want to have a good laugh at this board’s ability to predict the market 
The fact is that no one has a clue what’s going to happen in 5-7 years. I don’t think people could have predicted what’s happening within the past month or two in the past 6 months, let alone the last year.
There’s just too many factors that could either contribute to or negate from the growth. If the Pokemon game on the Switch turns out to be a major success and appeals to a wide audience (i.e., the adults that grew up on Pokemon as well as yungins), growth could be meteoric. If the next series of Pokemon cards turns off players from competitive TCG or collectors (either by increasing prices too high, unattractive art, uninteresting high value cards, etc.), you might see things stagnate.
Then there’s the whole issue with, what feels like, the political uncertainty going on in the US. Will that contribute to domestic economic issues? If so, that may halt growth for quite awhile.