It's not categorical and there are many signature models that get discontinued for normal business reasons and stay relatively static or go down in value. While Mayer may be the most obvious recent example, a wider view of the market around used signature guitars shows many other instances where a discontinued or limited-edition artist model steadily increases in value in the years following the end of their production often selling for more than the guitar's original retail price.
A less-discussed effect, though, can be traced through the sales data here on Reverb, as prices on the now-discontinued Mayer signature Fender model started to creep up and up. This rather public breakup between a famous guitarist and famous guitar brand-and the resultant new model-had the immediate consequence of giving the online guitar community plenty of fodder for debate. Mayer left behind the signature Strat pantheon of Clapton, Yngwie, and SRV to join up with Paul Reed Smith, eventually unveiling the Silver Sky, a Strat-shaped signature model that would prove to be one of the more controversial guitar releases in recent memory.
When John Mayer announced his split with Fender in 2014, he initiated what would become one of the more discussed chains of events to take place within the guitar market over the past decade.
