IVAS is being engineered at Belvoir where ENVG was developed. IVAS is an outgrowth of ENVG-B so it must integrate with fixed features i.e. RTA, FWS, multiple sensing, the Network etc.. Highly unlikely they are changing displays horses in mid-stream.

Job Description We are seeking a collaborative self-starter to join the team during this exciting time As an Adaptive Squad Architect, you will be providing Systems Engineer expertise as the Adaptive Squad Architecture Directly Responsible Individual (ASA DRI) under Project Manager, Integrated Visual Augmentation System (PM IVAS). You will be responsible for the management and implementation of the systems engineering process during the design, development and delivery of the ASA. Successful job performance requires a thorough knowledge of the Systems Engineering Management Process and Implementation throughout all life cycle phases; expertise and knowledge of software life-cycle sustainment.

https://www.recruit.net/job/system-architect_fort-belvoir_jobs/96DB28B5D42C602E

And from the IVAS SOO:

The IVAS Prototype Project seeks to provide a HUD 3.0 and integrated STE Squad capability within the Squad Architecture in support of Army, Marines, and Special Operations Forces within 24 months. The PPA shall deliver a baseline standalone STE Squad capability within 12 months, and STE Squad capability integrated into HUD 3.0 within 24 months. This complete IVAS capability shall be suitable to begin production as early as 4Q20 to ensure clear overmatch in Close Combat engagements and drastically increase Squad Lethality.