Singular "pant" has recently-ish become accepted fashion industry jargon: "Our spring collection includes a khaki pant and a capri pant". I've started to see it creep from there into everyday language.
This might stem from noncount noun rules rather than any particular trend for the word "pants".
Typical example is the word _water_. It is noncount except when talking about types of water. E.g., this year we introduced a vitamin water and an energy water to our line of beverages. By extension, you can pluralize it: we introduced two new waters this year.
I don't disagree that pants might be slowly becoming countable, just noting that the particular verbiage of "a capri pant" or whatever can be produced using the usual rules.
