It's not as easy to add courses as many WGT players think it is.
So don't get your hopes up for hundreds of golf courses, let alone for thousands.
WGT and a course have to enter a legal agreement that lets WGT use the course for play online. So the golf course has to presume an association with WGT is in the golf course's best interests. Some amount of negotiation has to be done to hash out the agreement and financial details.
WGT and Pebble Beach renewed and changed their agreement so PB could be added for 18 holes of stroke play before the next US Open that will be played there in 2019.
Apparently, golf courses on WGT pay WGT to be included for play online.
From start to finish it takes WGT about 6 months to produce a new 18 hole course for stroke play. The photography, 200,000 to 300,000 photos, and the GPS info needed takes a couple of weeks to record. Play on the course being photographed is disrupted to some extent during the weeks the principle photography is being done.
Processing the hundreds of thousands of photos/GPS data and mating them to the programming takes up the rest of the time.
If WGT could cut the production time in half, they would still only be able to add a maximum of 4 new courses per year. Of course WGT would also have to find 4 courses per year willing to pay to be included for play on WGT.
For a time WGT had an agreement with the Royal and Ancient to regularly add British Open courses, but that agreement ended after we got St.Andrews and Royal St. George's.