Currently overhauling KSLC, and working on two US international airports. More info to come regarding the two new US airports in the coming months when we're satisfied with progress work.
KSLC was already a free upgrade from FSX to P3DV4 so having that in mind, and the number of hours and resources we are currently investing in this major overhaul, there may a be a small fee upgrade this time around. Note that the real-world airport is currently undergoing major construction with new main terminals coming on stream. New and old/current taxiways, lighting, etc. are also being built so we have to re-work our sim version as well. More importantly, MSFS20 will be the target sim platform for the KSLC overhaul as well, but until we know what the new MSFS20 SDK would look like, we can't predict what fees may be involved. MSFS20 is a different ball-game altogether and is still an unknown at this juncture.