We keep hearing that Facter is going to start supporting structured facts at some point in the not-too-distant future. Once that happens, we will need to be able to support them in PuppetDB. Presumably this is simply a matter of storing them, which could be as simple as just serializing them to JSON and stuffing them into a varchar/text field.
However, if we need to support queries against them, things could get more complicated. Need some requirements specification here.
I'm not currently aware of any UI functionality in PE that is planned around this, so I think prioritization is more of a matter of knowing when this support is coming in Puppet, and making sure we're ready in PuppetDB at the same time. (michelle.johansen , wagner please feel free to weigh in on that if I've gotten anything wrong.)