Bright. Bright as the brightest star currently in the whole universe.
On the other hand, there might be a chance that the future of cryptocurrency might be as dark as the largest black hole in the universe.

What I'm trying to say is that, the future of cryptocurrency can't be predicted at all. We know that past performances is no guarantee of future results. What happened in the past might not happen in the future. I'm optimistic when it comes to Bitcoin, and the whole cryptocurrency, but I can't just remove the fact that there might be a chance that we might see a new invention in the future that would be better than crypto. I mean I don't know what it is, but anything can happen, right?

I guess what I will say to you OP is that, if you believe that crypto will still be there for the next 5 years, invest into it, then sell after 5 years or at least during that time frame. You asked a wrong forum when it comes to that IMO, and nobody can answer you that accurately that's for sure. I guess just Good Luck OP.