Hmm, WannaCry doesn’t necessarily need you to upgrade. You can just download the update patches Microsoft released a while ago in March.
Having said that, I like the idea but it’s a bit too optimistic.
First of all, many Enterprise level companies have Intranet IE systems (banks mostly) that run in compatibility security protected mode (if not ugly Shareapoint).
That forces IE7 on most of them. You can disable that using meta tags to use edge versions but really how does an Enterprise company with thousands of workstations upgrade all of them to win 10? That’s like a huge cost and they will surely prioritise other investments.