My suspicion is it could be sought after (I'm 50/50 on this until we start seeing confirmation of that in many years to come) because it's one of the higher spec special editions. We just won't know how many have sold for a few more months yet, but it could be considerably lower than the other special editions. I just don't know whether it will be 50 sold, 150, 250 or 500. If I had to guess I'd guess <150 sold, but wouldn't be surprised if it's considerably lower, or higher.
What I find interesting is the special editions in the lower specs sold out really well for Jeep (hence why the 75th could have sold well, and be higher sales than I may imagine). e.g. Night Eagle sold 270 in just 6 months, out of the 350 limit. And Dawn of Justice sold 340 of the 500 limit over the same period. I think DoJ sold out now, but we won't know until the Q3 figures come out. I think Jeep will be happy with that sales performance just on the special editions, let alone their regular sales.
The main thing in collectors values is does the vehicle become an icon. There are not many 4x4 icons (Landrover Defender springs to mind) v sports cars, but it's just possible people will catch on to how revolutionary the Renegade was for the 4x4 market. The other factors being how many fans there are for the vehicle and brand, and clearly there are a lot of fans/enthusiasts here!
On the other hand, there's been loads of special editions in the past that just are not sought after with no demand. But their brands aren't iconic nor are there enthusiasts. I'm also conscious worldwide production of the 75th is pretty high really, so quite a bit of worldwide supply (especially in USA), albeit the UK version supply should be limited (and people in UK only really care about the RHD vehicles).