iPad sales are flat, but just because more and more people aren’t buying a new iPad is not indicative of a failure on Apple’s part.
Quite the opposite.
People seem to be quite content with their old(er) iPads. They’re likely not seeing the value in buying a new one if the old one is serving their needs. In many ways, users may be treating iPad like it’s a classic PC – not expecting to upgrade this computer until it breaks.
People continue to use iPad as a PC replacement, too – including buying items through Apple and generating revenue for the company in tow.
How is that anywhere near a failure?
Yes, the onus is still on Apple to drive value (and revenue) through hardware improvements, but even when it can’t sell a user the latest iteration… at least that person is probably happy with their current iPad.
I don’t think a happy user could be categorized in the “failure” column. If anything, Apple needs to further adjust its expectations and create more value in services, software, and ecosystem to compensate accordingly.