So the question is, How does BYU make itself the most attractive candidate come that time?

Two options:
1. Schedule difficult schedules that fans "like" so we can travel and say we've played "(insert solid/great P5 program)". Downside, we are a perennial 7-5 type team that doesn't sniff the Top 25, very little player accolades, and a fan base that tunes out after 2 losses. Upside, we get 1-2 wins per season against a solid P5 school like last year with USC and Tennessee. The fan base gets to travel to some blue-blood college football stadiums. I don't know how a P5 conference would look at this. 7-5 with no national attention doesn't really move the needle, especially with a less energized fan base. Potential for a really solid 9-10 win season every so often.

2. Schedule similar to what Jarom is saying. The downside, SOS gets called out and the chance of making the CFP is pretty much non-existant (which is the case with #1 as well) and some fans may tune out because we play a weaker schedule. Upside, we win and we win a lot more. Top 25 is more attainable, national exposure, and I'd argue a reenergized fan base. Regardless of level of competition, fans want a winning program and winning attracts. The potential for an NY6 bowl game is much higher based on the potential to finish a season with 0-1 losses.

If a P5 is looking to expand, I think going the route of #2 makes BYU more attractive. A more energized fan base and eyeballs on TV are $$$ that a conference is going to care about. I think winning and Top 25 rankings solve a lot of problems when it comes to recruiting. Not that we will jump to a top 25 recruiting program. I'd be satisfied with a top 50 on a consistent basis.

The goal is to make BYU the most attractive program when the potential expansion comes. Creating a culture of winning and energy is going to be that solution, IMO. The path to get there is the same path BYU has always taken, being a big fish in a smaller pond.