Your assertion does not make it true. Unlimited wireless broadband is not sustainable for both home and mobile use. Maybe it was about four years ago when Sprint started offering Clear WiMAX as its 4G solution, but circumstances have changed.
At that time, smartphone penetration, especially 4G capable smartphone penetration, was much lower. Not to mention, peak speed expectations were also much lower. At 10 Mbps, Clear was thought to be blazingly fast. Now, 10 Mbps is considered to be on the slow end of the spectrum. On the home broadband side, cutting the cord to use streaming video was not nearly as prevalent as it is today. All of that adds up to a practically untenable situation.
Like it or not, the big money is in mobile, not home broadband. Even VZ and AT&T -- if they get their way with regulators -- want to exit the slow growth home broadband business. So, when forced to choose, Sprint will side with mobile.
AJ