If what Look says is true, Garmin needs to redesign the pedal axle. Look had to do it too, but since they're using their own pedals, they could without rocking the boat too much. Just look at the pedals - they differ substantially from the outside (and the inside).
Note how thick the axle is towards the outside of the pedal
(Image from Look)
In comparison, the regular Keo Max's axle tapers and ends short of the outside of the pedal
(Image from Look)
Garmin is sourcing third party pedals so that makes the job of redesigning the pedal a bit more difficult.
Unfortunately for them it's not a simple thing. My understanding is that the pedal axle really can't be tapered because then it flexes too much, causing power readings all over the map. Either they need a much more rigid (or predictably flexible) material or they need to significantly beef up the axle.
It's one thing to ask a pedal manufacturer to print your name on the outside of the pedal, or use a different color plastic for the body. It's another to ask them to redesign their actual product so that it fits your needs.
If they want to stick with pedal based power (and the left/right measurements it offers), Garmin has a few choices that I see.
First, they can make their own pedal. This is pretty complex, with all the standards and cleats and all that. It also costs a lot, and, frankly, making pedals isn't Garmin's core business. Which, of course, is why the outsourced the pedal to begin with.
Second, they can partner up with a pedal manufacturer to create a new pedal specifically for the Garmin system. This obviously isn't working with the current pedal supplier. I imagine that it won't work with Speedplay, since they severed that relationship when they first bought the pedal power concept.
I do see the possibility of them teaming up with a different pedal vendor, maybe one that makes boutique type pedals, that is a direct competitor to Look/Polar, and is willing to work around Garmin's needs to market a version "1.1" of whatever pedal they currently sell.
As an industry outsider, Mavic pops to mind first. They just started making inroads into the pedal market, they are pushing hard on other gear, and they have a well established business that could support some of the R&D costs such a pedal would absorb.
Third, Garmin has literally hundreds of millions of dollars, if not billions, in revenue. I could see them simply buying someone who can make the pedals for them. They'd have whatever secondary business (think of someone that works with carbon, aluminum, and bearings, so maybe wheels or cranks or hubs or similar).
They'd have a built-in option to put the power elsewhere (like a better BB version or some other place no one's used yet), and they could have the company create a pedal specifically for the power system.
Again, as an industry outsider, I'm not sure who is on the market, who is willing to commit to pedal development. The company would be a smaller boutique type outfit, maybe a Chris King or an Enve.
One thing is for certain. If Garmin doesn't develop something, someone else will, perhaps someone from the list above.
Good for us riders. Bad for Garmin.