Sortof.

Only CO elites can Y-Up at time of booking (NW elites?? - I think not but am not certain). But, after all the elites are cleared at the gate if there are any Y fares still out there they will also be cleared. If they don't clear they will get a coupon for an upgrade on their next Y/H fare within 90 days that can be confirmed at time of booking. Not sure which bucket the coupon comes out of, but that "benefit" does exist.