I can see the A-Sun being interested in ETSU and UTC (and WCU isn't any further away than ETSU), but, ETSU (and WCU) would be well out of the current footprint - it's a long haul from Johnson City to Conway, Arkansas. I suspect ETSU would choose geography and basketball over tuna. Chatty would be a better geographic fit, but they also take basketball seriously and already get to play Jacksonville State in football many years. Unless the A-Sun becomes a multi-bid FCS powerhouse, I don't see how a move like this would benefit the Mocs.
The A-Sun would need 6 teams to get a playoff spot, so I suspect they already have someone else in mind to get to 6.