Hello,
I don't think you necessarily need to use physical hardware - I was just trying to point out that vCPUs do not perform quite as well as physical ones. There is a 'decay factor' to keep in mind, described in the Hardware Deployment Schemes doc I linked previously, and if you want to use IMC in a virtual environment, I always recommend going above the requirements listed in the doc for physical CPUs.
I've done IMC installations for 5k-15k devices on virtual machines and they work just fine. It's a matter of scaling the virtual hardware adequately and not just going for the bare minimum requirements - and also using a remote DB in such cases.
As for your migration, I would not recommend using the same system you run currently, as any issues would cause downtime for IMC. My suggestion would be to set up two new VMs, one for IMC and one for the remote DB. Though you would not have issues with one physical and one virtual machine either.
Make sure they are sized appropriately, install DB and iMC (exact same version), and then perform a migration from your old system to the new one. That way your network monitoring system won't be down if you encounter any 'database headaches' or other potential issues during setup.
There should not be any significant issues setting up the DB or migrating it, as there are detailed guides for every edition of MSSQL in relation to installation for iMC. If you run into trouble you can always ask here or open a support case too.
Centralized Deployment Guide with Remote DB: https://support.hpe.com/hpesc/public/docDisplay?docLocale=en_US&docId=a00094606en_us
MSSQL 2012 Installation Guide: https://support.hpe.com/hpesc/public/docDisplay?docLocale=en_US&docId=c05367564
Migration Guide (after the installation is up and running): https://support.hpe.com/hpesc/public/docDisplay?docLocale=en_US&docId=a00075552en_us
Keep in mind the requirements listed there, to ensure you migrate successfully:

Hope that helps!