A difficult question to answer but we do have some indicators (but no proofs). First, you have to understand that Hip-Hop "fashion" has always taken its style from mainstream fashion, especially the more expensive brands. What's special about Hip-Hop fashion is how it can combine several styles into one -- becoming something unique in itself. Mixing various "snob" brands with top-class sportswear has been the norm for most of Hip-Hop's history. It's kind of like sampling, which borrowed sounds from a vast selection of genres. As long as it's phat, we will rock it, is the motto!
This Phat Farm advertisement illustrates Hip-Hop preference for luxury brands and the lifestyle that's associated with it
However, in the 90s we saw something unique (the were just unique) when actual Hip-Hop brands started to become viable brands. They were marketed towards the urban (ie African-American) markets, but as Hip-Hop was growing rapidly in the underground, these brands were sold worldwide. It was entrepreneurs like Karl Kani (self-titled & Cross Colours), Puff Daddy (Sean John), Russell Simmons (Phat Farm), and Daymond John (FUBU) who made their dreams come true through the fashion avenue. These brands grew fast, however, they fell even faster due to the changes in fashion as well as overreaching beyond their target markets.
So what happened to Hip-Hop fashions after the millennium change?
Well, mostly it's been more of the same eg. following mainstream trends (strange looking skinny jeans) and retro styles (predominantly 90s) which everyone on the globe has been following. If there is anything new in Hip-Hop it must be the collab frenzy. Which is in fact as old as the 80s, think Run-DMC's collab with Adidas. It's just much more common these days. Mainstream brands don't know how to innovate any longer so they rely on the cred from Hip-Hop artists to sell their products.
Kanye's newest creation, Holy Spirit
But let's be honest, there is in fact a man who is really doing his own thing in Hip-Hop fashion anno today (and since 2007), his name is Kanye West. Love him or hate for his Trump allegiance, this man is a genius, and his products (Yeezy) reflect that. He's doing what mainstream fashion designers have done for eons, but he's doing in a Hip-Hop way. Truly legendary.
So what does the future of Hip-Hop fashion look like? A solid prediction would be a continuation of following mainstream luxury brands and if we're lucky more designers from the Hip-Hop will be inspired by Mr. West to do their own thing in an authentic way that doesn't rely on solely collabos.