Standard switch migration to Logical Switch
When starting to use VMM as management tool for already existing Hyper-V hosts, It should be possible to migrate the current Standard Switch to the Logical Switch, whitout deleting it and so on.
You can now use VMM to convert a Standard switch to a logical switch
Lyndon Frei commented
seems like this will be a feature in SCVMM vNext... http://www.danielstechblog.de/convert-standard-switch-to-logical-switch-in-system-center-2016-tp3-vmm/