It will be worth more than the competing products (all else being equal), but it won't be worth twice just because it lasts twice as long.
Absolutely agree. You rightfully point out broad simplifications that I made, though I think we agree that there's still an incentive for companies to build better products. Even if the price of the new bulb lower than 2 USD, but above 1 USD, the produces has an incentive to sell it - lower sales costs (you need to do it once), lower warehousing costs, etc. On the other hand the new technology can be more expensive than the old and offset these benefits.