I don't think that application virtualisation would change the licensing requirements for applications (e.g. per user or per device). So you will need to ensure you can still comply with those requirements, in much the same way as you need to account for
licensing when delivering apps via Terminal Server/RDS/XenApp etc.
Quite frankly, software vendors who drag their feet can take a hike. We need to deliver applications as quickly and dynamically as we can and if they don't get on board, they are getting in the way of their clients saving on deployment costs.