J-36 will enter in service in 2031-2032.. by that time we will have advance variants of WS-15 in production.I think the first three years of service may not have the VCE to go with it. Considerations still must be made for usage of WS-10 and WS-15.
so either WS-15 or WS-XX
WS-XX has entered in full scale prototype stage. it won't take much time.