I would like to see the marketing lingo Apple or anyone else uses to claim that a certain material is superior to Titanium. Go ahead, try it.
Personally, the 15 Pro is nearly perfect for me. It is the largest-sized phone I want to carry and is less than 8 ounces with a minimal case that shows off the Blue titanium finish on the sides. I'm aware of the heat conductivity problem, though in my use the 15 Pro doesn't perform noticeably worse than any of my previous iPhones (X, 12 mini, SE 1st gen). If we follow the normal three-year cycle for major body styles, we shouldn't expect huge changes until the 18. Even then, what would that magic material be?
I remember the OG TiBook. People lusted after it. In two years they switched to fully aluminum cases which held up better over extended periods. The iPhone 15 Pro/16 Pro has very few moving parts, minimal plastic, and Apple has seemed to figure out how to make the finish last. My 15 Pro has zero scratches, which I couldn't say for any of the previous stainless steel or aluminum products after 1+ years. They can keep tweaking the frame design by adding structural aluminum that does double duty as a heat sink. If Apple wants to unleash a cavalcade of colors for its Pro line then sure, aluminum is the way to go. Other than that they should stick to titanium.