An abrupt switch to a 3-4 makes no sense from an on-field performance perspective. the bills have a unique group of players acquired specifically to play the 4-3 read and react cover-2. A carefully planned transiition to a 3-4 would make sense to be implemented only after the proper building blocks are actually acquired, such as a stud NT.
The more likely explanation for an abrupt change to a 3-4 under a DC who has never orchestrated a 3-4 is that it will provide sufficient smoke screen to explain the gutting of the over-priced defensive line who clearly won't fit the 3-4 scheme. Expect Schobel, Denney, Kelsay and Stroud to not be on the roster much longer, but much more cash to be in Ralph's vault.
The coaching staff full of "teachers" will have their hands full trying to compete with young cheap replacements. sort of like the challenge Kugler had last year in trying to protect the QB after having his OL gutted before the season.
Without a salary cap floor, there is no telling how low Ralph will take the payroll. in Brandon's prior life, the Marlin's typically operated with a payroll under $15 mil while the yankees were at $200 mil.