Well, if you search the Intel/Altera PDN notices they do provide exact guidance on the upcoming EOL of a product.
Typically they provide 3-6 months of remaining last time buy window, and 6-9 months to last time product shipment.
As to providing much longer term (ie, 7 years) of guaranteed production that comes with responsibility on both sides.
As a customer, you must provide contracted (guaranteed) orders and acceptance of shipped product.
You can't decide 3 years in to cancel all your orders. So there is a huge risk on your part.
In return, Intel/Altera will continue to produce certain parts under contract even when they are no longer cost effective.
No significant customers today will look at design in of EPM7064 devices for new product, even tho for a small customer it might make sense.
And like it or not (I've always worked for very large consumers of semiconductor parts, especially Intel/Altera) and because we bought hundreds of millions of dollars per year of devices we can el primo treatment. Support, access to new devices, technology road maps, advance notice of product family changes. That is just the way it works. Small guys that buy thru distributors don't get this info.
You may not like that, but that is how it works.