Not necessarily.
According to the Forbes list from 2013 (the one where Buffalo was listed with a "team value" of $870 million), only 7 teams were listed with a value over $1.3 billion—Dallas, New England, Washington, NY Giants, Houston, NY Jets, Philadelphia). The article was written a year ago, and at the time they said the values of NFL teams went up by about 5% from the previous year, so those numbers are likely inflated again by another 5% or so right now. But generally speaking, those numbers are around what they are now, so most teams were not already valued at more than $1.3 billion.
If the Bills, valued at roughly $900 million, are sold for $1.3 billion, that's nearly 150% of their current estimated value. Do the other teams now reap a similar benefit?
If the league's most valuable team, the Cowboys, were valued at $2.3 million in 2013 (more than 2.5x the value of the Bills), and the Bills now sell for $1.3 billion, do the Cowboys maintain that 2.5-fold value over the Bills and are now estimated to be worth $3.4 billion?