Have you ever requested additional post-EOL LTBs from your board OEM, only to find you need more boards later on?
Board OEMs care about their customers. If these OEMs could continue to provide the quality products their customers have come to depend on, most would. For the majority of customers, upgrades are a welcome and viable option; however for some, upgrades are not possible.
Board OEMs do what they can. Most offer some kind of lifecycle assurance plan that can extend support for 5-10 years after EOL of the board. Unfortunately, funding and forecasting for unusually long and sometimes indefinite program lifecycles leave these plans out of reach for many customers.