To see the interest in XRv which can be thought of asd the next-gen XR4U. XRv's first release is 4.3.2 as you have seen, but this is a limited availability release. Below is some general information, but please do contact your Cisco account team for more information.

IOS XRv is a Virtual Machine running the IOS-XR operating  system.  The VM combines Route-Processor and Line-card functionality in  a  single image, offering full control-plane and management plane   capabilities as contained in the regular IOS XR operating system.   Release 4.3.2 will only offer vRR version with limited availability, no   Demo and Simulator  offering.

With XRv we are planning three types of images: demo, simulation, and production. The differences in the images have to do with the data plane rate limits and licensing needed.

There are 3 main use cases for IOS XRv:

XR familiarization and education (Demo version will NOT be offered in Release 4.3.2)
Configuration staging and testing- Network Modeling (Simulator version will NOT be offered in Release 4.3.2)
vRR: virtual router production use cases, starting with vRR (Route Reflector is the only version in Release 4.3.2)