Only reason I can think for Lotus to want to do that is because they expect to not be able to provide warranty service/parts beyond 3 years from now, which they'd be required to do otherwise.
I agree with BJ^2 that you are overthinking it; the above sentence makes no sense.
A warranty is not an iron-clad, hell-or-high-water guarantee that something will happen. It is a contract like any other. If the entity you have a contract with cannot deliver on that contract, you can pursue them through the courts (or via arbitration, if that's what the contract says). If the entity goes bankrupt, you join the list of creditors with claims on the estate; if there isn't enough to settle all the creditors, you may get little or nothing.
The contract is only worth what the counterparty is good for, and a vanished car company wouldn't be good for much. Thus, Lotus would have no incentive to start warranty periods sooner rather than later -- quite the opposite in fact. This is setting aside the fact that planning several years in advance for a bankruptcy would be a foolish, not to mention fraudulent, thing for a company to be doing.
There's a common misconception that somehow the (US federal?) government "requires" car companies to carry a full stock of parts, or provide a certain level of service, or otherwise honor warranties no matter what. There are indeed laws specifying certain aspects of warranty conditions, for consumer protection and public interest reasons, e.g. around emissions equipment. However it's important to realize that is not the same as the government enforcing an individual's warranty, and it absolutely does not mean that there will be any recourse available to you if your warranty counterparty were to be liquidated.
Anyway, back to the original point, I would agree with you that having a warranty adds value to a car... but only to the degree one thinks one can draw on that warranty. If your only dealer is 800 miles away, or your dealer tech's a hack, or (Colin forbid) Lotus goes away, well then, you probably shouldn't be buying one of these cars unless you're good with a wrench!