As you said.. there will always be those that love the charm of Traditional Rifles and what they can do. But I do believe the projectiles and optics will make great advances in the muzzle loading market place. We are already seeing that. Look at what has advanced in just the last ten years.
Another concern of mine would be in the political forum. It is possible, the hue and cry of certain political power groups will make sure that the use of a muzzleloader is for amusement only and not for hunting. Perhaps in 50 years, hunting as we know it will not exist.
One other concern is the use of LEAD. Oh yes, the DREADED LEAD BULLET. That magic metal that animals eat and then die from it. That magic metal that comes out of the ground and has been around for hundreds of years. I can see again, political groups outlaw the use of lead. Imagine trying to shoot a traditional rifle with something non lead.