I think that as time passes and the "Fab Four"'s day planner books get filled with the specific engagements they're going to do, we'll see Harry and Meghan at events together but it won't be the norm. Two can cover much more ground and spread their support and interests separately than they can together.
What I find touching and actually a brilliant idea is that so many things that these younger royals take on can and do mesh together and that nearly all of them can benefit from their "Heads Together" mental health campaign. For example, just recently its been suggested that with Harry's Sentebale and Meghan's National Theater patronage, it can be combined for a joint purpose. We may see (and this is just speculation) Kate's involvement in Place2Be (making a lifetime of difference to children in schools) and Meghan's Smart Works (free clothes and job interview training) join together for an event that highlights *both* of the patronages working together. Or, we'll see Meghan and Camilla jointly doing something to benefit animal rescue shelters. You get the idea. ?
Getting people to work together for a purpose is what happens when you umbrella interests and goals together. In a way, I think this way of doing things is pretty much an advancement in how the "Firm" and the royal workers are going to do things in the future. Meghan and her separate and personal interests and patronages is increasing the size of the umbrella.
ETA: The more I think about it, the more I'm coming to realize that as much as we admire Harry and Meghan as a couple and for some, focus on this couple, it would pay us well to remember that these two are basically, in everything they do, a part of a bigger picture where they work with a team whether it be the "Firm" or the Royal Foundation. As the idiom goes, "there are no small parts. Only small actors." Dabbs Greer, a bit actor, once said, "Every character actor, in their own little sphere, is the lead."