Let's take a look at others that come to mind who have reneged on WSU in the recent past, and how they ultimately faired:
Adonis Smith (Northwestern): Just jumped ship over the weekend. Based off watching a couple of Northwestern players succeed in the East/West Shrine game. That right there just goes to show you how much recruits follow things like this. An all-star game made you change your mind? Oh well, we got Galvin and Sankey coming in.
Geoff Meinken (Stanford): Redshirted last year, after choosing the Cardinal because of their top tier education.
Trey Henderson (USC): Closed the chapter on his football career after injuring his knee last year.
Brian Baucham (USC): Not playing much, still young, but appears to be on their 2 or 3 deeps.
Vincent Joseph (USC): Per Scott Wolf of the LA Times he failed out of USC as a sophomore.
Luis Vasquez (ASU): Switched his commitment to ASU, and even was a JC All-American before quitting on WSU. One of the reasons for his change-up at the time was when Robb Akey bolted for Idaho, Vasquez switched to ASU. Had 8.5 sacks in 2 years of starting.
Marlon Wood (UW): A DB who went purple and gold. Marlon Wood was a contributor, but lost a season when TyWi chose not to give a group of guys their redshirt senior years.
Kai Ellis (UW): I believe academics led him to a California JUCO. But he even appeared to be set after earning his AA to come to Pullman, before switching to the UW last minute. His career was ho-hum, aside from costing the Cougs the 2002 Apple Cup, and a rematch with the Ohio State University in the Fiesta Bowl/National Championship!
Looking at the above data, I believe it is safe to say the grass isn't necessarily greener. One thing is for sure, Coach Wulff & Co. won't be drinking coffee until those LOI's are signed and in-hand.

"Get Them to Sign on the Line Which is Dotted....A-B-C. A - Always, B - Be, C - Closing. ALWAYS BE CLOSING!"