In general or just in the field of cryptocurrency? Well, scientific breakthroughs and innovations depend on the needs of mankind. Since the rest us are now suffering from the pandemic then for me the next big thing that we can foresee is the invention of the Covid 19 vaccine/cure because that's what the world badly needed right now .

But if you are only talking about crypto, I can't see anything so far. I mean bitcoin is the greatest and no alt can defeat it until now despite offering greater features .