Brandon isn't anywhere near fielding a CJFL team for 2 reasons:
Finance: It costs approx 350,000 per year to field a team in the PFC, driven by very high travel costs. Unless a very wealthy benefactor steps up, it's not likely to happen. The costs are lower in the BCFC as they can "day trip" to most of their games.
Market Size: There have been some very good football players come out of Brandon, but it and the surrounding area just don't have enough players to compete at a national level. There are 3 high school teams in Brandon, that simply is too small of a pool of players to draw from. They are better suited to the MMJFL, where the costs are much lower.
Chilliwack wouldn't be able to compete in the Prairie Conference. Actually none of the BC teams would. It's been 10 years since a BCFC team beat a PFC team in any game (there were a few inter-locking games a couple of years ago) and it really was only a small window "the Andrew Harris years" when a BC team won (06, 08, 09), The 07 game went to the PFC, as did every game for the 5 years before. The level of play is just much higher on the prairies.
Most CJFL players that go on to the CFL do so through U sports. Typically a player will be with a CJFL club for 3-5 years and then jumps to the university level and plays there for another 2-4 years. There are some who go from CJFL directly to the CFL, but they are rare.