The primary reason I bought an iPhone X is because I want dual camera but I don't want a Plus-sized iPhone, so an X-Plus announcement will not surprise me or tempt me.
Will there be a new X-sized iPhone as well? Possibly. Will the new models have slightly upgraded specs, a new cool feature, or a refined feature like a smaller notch? Probably. Will it make me regret getting the original iPhone X? No, but I suppose it might make me upgrade, although that is unlikely. It all depends on how much the new or improved features mean to me, and one year usually doesn't make a huge difference for my needs. I'm waiting for the forward facing dot projector that can scan and identify an object in front of me and immediately give me information like the dimensions, make, model, specifications, instruction manual, and the option to order the object or compatible parts/refills. I figure we are two years away from that.