Lots of fun patterns and themes here.
https://www.shabbyfabrics.com/Wall-Hangings-C1657.aspx
I would first research why the drop in participation. Question the members as to what they are interested in doing.
A BOM that can be made into either a wall hanging or a quilt might gather support.
Would a theme for a year (or 6 months)with different members responsible for each month pattern and colors work? Could be fun!
Perhaps the members don't want to keep the BOM project. It could be donated so that a guild quilt is made for a charity function or raffle.
Good luck!