I wouldn’t put it that way - after all, Fairphone was founded before Ara was even announced.
Granted, the FP1 wasn’t modular, just repairable, so later FP devices may have been influenced by these modular concepts. Still, the modularity of the FP2 and FP3 didn’t spring from a drive for upgradeability but one for repairability. The idea people have about Fairphones being upgradable comes mostly from the lofty promises of those unrealised concepts - in fact, for the FP3, Fairphone have gone to some lengths to make clear that the device isn’t built for upgrades, but for repairs.
So long story short, specialised addons are most likely going to come from the community, not the company. A number of custom FP parts have already been designed and produced by community members, notably a USB-C module for the FP2 and a prototyping shield that allows the user to experiment in a variety of ways.