I don't think the addition of several Allegiant flights a week to Las Vegas will have any impact at all on prices from BLI - SEA. I don't know if Allegiant code shares with any other airline, but I kind of doubt it since it seems to be strictly leisure flights to Las Vegas. I did check their web site to see about using them to fly through Las Vegas to other places, and you can't even do that, you have to book a flight to Las Vegas, and then a separate flight somewhere else they fly. I don't think BLI flight costs will come down unless another "real" carrier enters the market, and I don't see that happening any time soon. Until then, and as long as someone else is paying my travel expenses, I'll keep racking up the miles and the segments.