RE: What is the biggest challenge for Hive ?

I guess it depends if you mean the Hive block chain or the Hive token, but I'm presuming the former. Probably it's nature as an older niche blogging platform. A lot of the crypto market tends to chase the shiny new thing, which Hive hasn't been for some time. As far as blogging goes, I'm not sure how popular that really is - and, if you search for a blogging platform, you're probably going to get a lot of other results back first.