Well... Hoonigan's basically Ken Block: The Brand so it only makes sense for it to eventually go up in smoke after his death, a bit like how Top Gear went after the OG trio left.
I don't know if this is even a particularly controversial opinion here but: I could live without the Hoonigan cars in Forza to be honest. As cool as some of the cars are (the rally/Gymkhana cars in particular for me), I think equivalent customization options could just as easily "replace" some of those cars, especially in terms of widebodies (the Focus RS already has one) and maybe engine swaps (the og RS200 has none, the Hoonigan RS200 has two - guess which one is used more!).
Obviously interiors will remain factory-spec as long as there is no interior customization available, which is a drawback, though I guess in theory they could already add custom race-spec interiors as a conversion option (a'la NFS Shift) among the widebodies. Not saying they will - they'll most likely wait for a future Forza title to go "wow look new feature!" - but still.