Wheel it back 25 years ago, and Virginia Tech is a football independent. They get a little Metro Conference revenue, but I'd speculate it was for less then one million dollars a year. Now Tech is pulling down 20 million a year as a member of the ACC.

The schools that formed the Big 10, Pac 10, SEC and Big 8 have been mainstays on televised college football for 50+ years. But prior to the 1980s, the TV revenue was a small fraction of what it is today. The number of games available was also a fraction of what it is today, with only the major networks, ABC, NBC and CBS broadcasting games, only on Saturday. The scenario changed in 1991 when Notre Dame broke from the NCAA and signed its own exclusive deal.

Per your question though as to whether an outside school can join the blue-bloods, the response to your question is to look at Florida State and South Carolina. The two schools were peers of Virginia Tech in the Metro Conference. But they broke free, landing spots in the ACC and SEC.