I assume TARA 4 will follow the current edition's rules. This means 12 legs, and with 10 teams, expect the first leg to be an NEL.
I also believe that the race adapt a similar course to TARA 2.
My personal guess for the start/end country: Cambodia. TARA 3 had teams fly directly to their final destination in the starting country, but in a different city. Phnom Penh/Siem Reap would fit this pattern.
Since TARA likes to spend two legs in one country, here are what I believe to be the other countries that the producers will consider:
Bandar Seri Begawan
Everybody has there own view on this, but here are three things that I will predict:
1. The pattern set by ARA3 of no first leg NEL will be the one followed by ARA4, not the first-leg NELs of ARA1 and ARA2
2. The start city will be the end city, the pattern followed by ARA2 and ARA3.
3. The start city and end city for ARA4 will not be Singapore or Bangkok.
So, what is my guess on the start city and end city? Guangzhou, China.