Such an upgrade is possible with one requirement though - your Virtualization Extensions Service should be installed on a Management Server (because this is a requirement for Hyper-V support). If VES is on the Management Server, you can upgrade it to v7, then you'll need to upgrade collectors too (there is a way to enable Collector Auto-deployment during the upgrade, so that you don't need to upgrade them manually). Then import updated MPs and Hyper-V MPs.
If you have a license with both VMware and Hyper-V sockets, VES will work in hybrid mode (Hyper-v and vSphere) and you'll be able to configure data collection for both hypervisors in the same UI.
Additional information (including a way to enable collector auto-deployment during upgrade) can be found in the Installation Guide on the resources page: https://www.veeam.com/management-pack-s ... urces.html
Let me know if you have any other questions.