Sounds like Modulus itself is defunct (there's a long thread about this on TB).
That's a shame for us Modulus lovers, and it definitely impacts the availability (and probably the cost) of Modulus aftermarket necks (both full-on graphite and Genesis necks).
First - both graphite and Genesis necks were made in 34 in scale P and J styles). Even when Modulus was a going concern, the wait times for factory Genesis necks were somewhere between a long time and never. I happened to find one at a reasonable price from a dealer who was trying to close down his business. I did sell that neck some time ago, because I decided to go full graphite. If I had a Genesis bass right now, I'd hold on to it - cool instrument that will probably appreciate a bit based on lack of availability.
My guess would be that there are going to be a few Genesis necks on the used market, but at higher prices than when Modulus was still in business (whether or not Modulus was really producing them). I'd monitor Ebay and the used websites and put out some Want to Buy messages. Good luck.