I don't think romance options as they look now are how romance options come full release. For example, all of the Early Access companions are bisexual right now, which I think is less about being PC as some like to rant about, but rather a placeholder sexuality so that players feel they have more to choose from while it's only Early Access.
I don't see any reason why the writers can't/aren't already writing in poly options for romance or sex. Shouldn't be available to all companions, imo, but some should be open to it, some not, some may be written as initially open but later wanting exclusivity with PC. In other words opening up for three way dramas, as well. ;-p