Non-status F pax don't matter to them as much as 1K/GS F pax (while, of course the numbers will vary from route to route my experience -- mostly domestic narrowbody -- is generally upgrades aren't happening but a substantial portion of the front cabin has status. (Flying from CLE good luck getting a front cabin seat if you're booking less than 2 weeks out). Conversely, on wide bodies I've never seen anyone struggling for overhead space in the front. If I knew I was boarding late (e.g. no status) I may extend my time in the lounge relaxing and get to the gate when I get to the gate [I've posted before the way my brain handles travel the real me would never actually do this, but thinking about a rational traveler who isn't me].

But I'm sure UA and DL and AA and LH and ... have run the numbers and simulated impacts on revenue/loyalty. I'd say that my $27,000+ in spend (excluding tax) so far this year, most of it on premium fares, is more valuable to UA than a one-off F cabin purchase particularly if you account for the greater exposure surface for advertising/credit card offers/ancillary purchases [club memberships et al] that they can derive indirect revenue from. Certainly AA has calculated that differently (and as a no-status AAdvantage member that works to my advantage in when I wind up over there)