The only way Asics would drop Hall would be if
1. Hall asks for more money than the market will bear, a la Meb (or Meb's brother) or
2. Asics has really stupid marketing people.
Hall is by far the most marketable runner in the US with the general hobby jogger population. He gets by far the most publicity of any runner in the US, and from mainstream publications, not just running publications. Disgruntled fan boys will run him down on Letsrun just like they will run down anybody without a recent stellar performance. He has more of a devoted fan base than any other runner in the US. The average hobby jogger probably doesn't even know about Hall's DNF and withdrawal from the NYM, and wouldn't care if they did know.
My own view is that he got injured in an Olympic year which really sucks but the people knocking him are overreacting. People get injured in running. It's the nature of the thing. I think hobby joggers understand that better than the people on here who immediately go after Webb, Rupp, Solinsky or whoever whenever they underperform.
Finally, if Asics is really dropping the Hyperspeeds, that sucks. It's by far my favorite Asics shoe.