This is a misleading post, of course they can/will. Elon's comment is referencing a specific a memory bandwidth limitation of HW3 (1/8 memory). The solution is to upgrade to > HW4 as a retrofit.
The claim was that all Teslas with version three of their onboard computing would become fully self driving. That's now definitively untrue. But, it isn't as if upgrading to the version four hardware will guarantee that you can get fully unsupervised self driving. No Teslas no matter what hardware in them is ready for fully unsupervised self driving. It's just a new gamble. You pay your money, you take your chances.