I have been working on 6.2 for some years now. However I looked at 6.4 features and saw that some forms can use json as its form model. I wanted to know if this will also be possible with XDP form templates?
Correct for designing XDP and creating the field binding you have to convert json to XML and use it further. But going forward you may explore the Functionality available on Adaptive forms side. Introduction of FDM(Form Data Model) in 6.3 peered with the Adaptive form gives you high designing and modelling capabilities. You can leverage fragments, scripting , styling and HTML rendering also with OOTB functions and yet create powerful forms easily.