From what I hear, most of the G5 schools and conferences involved are trying to make their moves complete for next year.
BYU and the American teams will jump in the BigXII this summer, as will the CUSA teams making moves to the Sun Belt and American. This is not offical, but it seems administrators are working behind the scenes to get these things done. The schools I am unsure about are the two that started the process. OU and UT to the SEC this summer seems less likely.
...and I think I clearly outlined with the Big Sky is better than the WCC, currently. Big Sky losing SUU isn't great, but WCC's loss of BYU is way more significant and clearly puts the Big Sky cements Big Sky on top of WCC, and ranks them as the very best non P5 XC conference. Pretty soon the WAC, with CBU and SUU, could overtake the WCC, especially if another WAC team emerges as a national level program.