WTN announced as going forward.
Presumably the USTA is onboard.
The scale is from 40 (beginner) to 1 (pro)
with a ranking for singles and doubles.
Not clear yet if a deal can be made with UTR or
will go forward with WTN...
USTA along with the ITF and the LTA
have announced the WTN World Tennis Number Initiative.
Their intention is to create a new more versatile worldwide rating system.
Implementation will begin in the fall of 2019
They have a website which is worldTennisNumber.com