It's more complicated than that with G&L. G&L distinguishes their products with patented exclusive parts such as their bridges and pickups. They aren't like so many makers out there who can change spacing by outsourcing pickups and bridges with different spacing. They'd have to make their own from scratch and that's probably what keeps them in their current zone.
Maybe someone could simply ask them?
I could easily see them modifying the saddles on the existing bridges so that probably wouldn't be that big of a deal.
With these new monorail bridges and extra wide covered Bartolinis and EMGs, other makers (e.g., Ibanez, Schecter) can change their spacing all they want just by changing where they drill the holes for the monorail bridges. G&L would have to design and cast a brand new bridge. Cost per unit would be significantly higher than for their current 4- and 5-string Saddle Lock bridges because the sales potential would be low and startup costs high.
The sales potential would be low? Why?
Ditto for pickups. They make their own, which have exposed adjustable pole pieces. They would have to design new neck and bridge pickups from scratch with new tooling, again with a long expensive amortization period and low expectations on return on investment.
I already mentioned pickups, if anything that would likely be the biggest expense (though how big is an unknown). As far as low expectations, I'll wait to see how you came to that conclusion.
G&L isn't known as a 5-string thumb-popper's bass maker the way Warwick, Ibanez, and other brands are.
Maybe that's because they don't make a bass that's comfortable for that use with many players. The other brands smelled the coffee, so could G&L.
And there's always the chance that by the time they develop the new designs and parts and spend the money, the trend for wider spaced strings could die out. Look at how many guitar companies boomed during the shred period (Hamer, Kramer, BC Rich, Dean, Charvel, Jackson) and have had to regroup when shred lost its market share.
Two completely different things. I have no doubt that wide spacing is the farthest thing from a fad imaginable. You're comparing a guitar fad with a physically limiting component of a bass.
Unless bassists (and people in general) get smaller. I don't see that happening anytime soon either. Wide spacing has been desirable by many bassists since five and up strings came to be well over twenty years ago. It was a common complaint early on and savvy companies actually paid attention to it. Eventually. The glut of custom builders who base five string spacing is 19mm bears that out.