the only challenge that i can think of which really matters is adoption. and that is not something you can fix, it is something that is fixed on its own with time.
as time goes by more people find out about bitcoin and more of them start using it. some are merchants and some are users and they all make the ecosystem grow.
This.
Mass adoption is the biggest challenge facing crypto at the moment, in the face of the current FUD. As with most things I think the key to further adoption is EDUCATION- the more people understand how revolutionary this tech is, the more interest in the space. simple.