Oh boy, being PHX based, I really liked HP the 2-3 years before Parker took over and merged with US. I now only fly US when UA and WN are not available. That whole "charge for water" thing just totally turned me off.
I am guessing what is going on is that CO+UA = US squeezed out and having to switch alliance down the road. So, US is making a move first.
Maybe this will push CO into action. Maybe not.
In either case, I think both CO and US are a lot less customer-friendly than UA. For example, award fees, no E+, etc. So, I think if anything changes, UA flyers will get the short end of the stick.