I'm not really bothering myself to think or predict on what would be the marketcap on next years to come since no man or investor can able to know on what would happen ahead.For now instead on minding about 3-4 trillion on overall cap then it is much more realistic for you to think first on 1 Trillion cap achievement because we are even now struggling on breaking that 400B cap.
Cryptomarket do really have a big potential but it wont come to a point that we can easily reach out those numbers.