Hmm, well, the value of his shares are already exponential. The thing about milestones being linear with market cap is that it will take much longer to hit the first milestones than the final milestones. So the rate at which Elon earns his shares will accelerate exponentially.
But the key thing about this plan and how Elon rolls is that Elon is strongly inclined to focus the company for long term success even at the delay near term targets. As much as people complain about Elon missing target dates, I've never seen him sacrifice the long-term success for the sake of hitting of short-term targets. He is constantly positioning the company for long-term success, which makes critics think that he can't stay focused on near term goals. But for Musk, near term objectives only have value to the extent they position the company for long-term growth.
So for example, solving the problems with ramping up production are likely more valuable to Musk because the company is learning how to ramp quickly than merely to satisfy investors or even generate cash flow. To keep growing production 50% or more each year, Tesla needs to get really good at ramping up production because that's what they'll be doing constantly for the next ten years. They aren't aiming for flawless execution of a single ramp. They are aiming an impossibly fast ramp as a dress rehearsal for very frequent ramping. For example suppose that in 2019 Tesla builds 1M vehicles. Well, in 2020 they'll want to build at least 1.5M. Thus, they will be attempting to increase production by 500k in one year, which may include one or two product launches in that year. So naturally, Elon wants to challenge the organization to ramp up 500k in one year with the launch of the Model 3. He needs the whole organization to have that level of capability. He knows that the organization may not have that capability just yet, but he's going to be a tough coach and force it to try because that is the only way it gain that capability. By the time 2020 comes around and Elon wants to launch and build 500k pickups in year one, his team will be like, "No problem, we've got this." This is really no different than Elon crashing rockets in the quest to routinize propulsive landings. Sure, it exposed him and his team to the embarrassment of public failure, but I've got to believe that the experiences were highly motivating to his team. Elon keeps pushing the landings to the limits, even though this risks more failure. In the Falcon Heavy launch, they only stuck two out of three landings. But someday SpaceX will be sticking 100s of landings every day with absolutely no failures because many will transport humans. Elon is totally focus on achieving that level of performance in the shortest amount of time. So to get there, Musk is going to keep pressing limits and risking spectacular failure at every try. So am I worried about the M3 launch taking more than a year to hit 5k/week? Not at all, in fact, failure is the best way to train the team to perform at a much higher level. If Tesla is not failing on near-term targets, Musk is not driving hard enough to become a $1T company in ten years.