Tatoruzu There's no way IDW thought "hey, let's make a 7-issue mini-series."
Comics are often plotted out months or even years in advance. Seven issues is possibly the closest they could to end the story while still getting some return on the money they sunk into it.
If it was up to me they would end it with Jennika going on tour with Sheena and then flash forwarding years into the future where she is doing an interview.
“Yeah, well, we had a few hits but I got caught up on heroin and totally crashed. One day I woke up and found that my shell was full of shit. The weird thing was that it wasn’t even my shit. That was when I decided to put my life into the hands of my personal Lord and Savior Jesus Christ and get clean and met my husband who’s a potato farmer from Idaho.
“We never did find out what happened to Sheena after we attended that barbecue contest in Memphis.”