I hope you are right so very very much. Probably my biggest concern heading into Inquisition is this very plot line. I chose not to accept Morrigans offer, and it worries me that I may be punished for this choice in the form of lack of access to content, storytelling, or positive outcomes. I will be so very sad if it turns out that the OGB is the only way to solve some conflict in Inquisition, with no equal choices for worlds in which he does not exist. I just really want my wardens sacrifice to be ultimately meaningful, and not a mistake.
I have never refused to recruit a party member. Why would I? That's just quests and combat help I don't get. If I were to, say, not recruit Leliana, I would expect not to meet Marjolaine in Origins. The ritual is different, though. I expect my endings to have reprocussions.
For instance, we'll say there are three settings. The first is that Morrigan's plans have fumbled and she needs to readjust, after all, her son can't have a destiny if he doesn't exist. So she has the inquisitor help her change them. Let's say now that she has the grimoire, she needs Flemeth's staff, not Flemeth's Broomstick from Witch Hunt, but her weapon, and you take her along in Inquisition to get it.
The second is that the warden romanced her, but didn't do the ritual. Word gets out the child is that of the warden, or has claim to the throne through the warden, Alistair, or Loghain, or some such. Someone thinks they'll get a good ransom for him or gets notions of setting up a puppet-prince, and he gets kidnapped. The inquisitor has to get him back for Morrigan.
The third is when the ritual was taken, and Morrigan needs help preparing him for his "destiny." Maybe you need to get Flemeth's staff for him, or maybe someone finds out what he is and kidnaps him.
I'd also like to see him look different based on his father. Dark-haired if his father was Loghain or a human warden, light-haired if his father was Alistair, tall for a dwarf and short for a human if the warden was a dwarf, or Feynriel-like if the warden was an elf.
In all likelihood, though, to simplify programming, he's going to look like his mother.