From working with Dane in the early days of the WIRLF and then the JRLA, the main reason why the focus moved from West Indies to Jamaica was just based upon the level of time people had to invest in the project.
The original approach was to create the West Indies team to help establish a brand which would then be used as the vehicle to get into the Caribbean with the hope of then creating domestic leagues off the back of. This concept was expected to take a number of years, and naturally was the main focus, however when of course people on the ground in Jamaica popped up willing to create a league there naturally the focus shifted from the West Indies team to Jamaica.
Dane rightfully made the right call based upon the finite time, resources and money available and I think the results are there to see today.
Honestly based upon the way it has happened, I think it would be unfair now to expect Jamaica to go under a West Indies brand unless they initiated the move.