Do we need groups or can they be replaced with policies?

[aszs]

[philippemerle]

Do we need groups or

From my experience, group is a TOSCA construct little used.

can they be replaced with policies?

Yes. A policy can refer several node templates like a group does.

[lauwers]

Groups are currently only used in policy definitions as a short-cut to associate a policy with a collection of nodes without having to list those nodes individually directly in the policy definition. I'm not aware of any other uses for groups.