Its a tough question...some good answers offered so far. Its hard to pick something that matches the gun in all regards, but has also not yet hit Python status. I was going to mention the Colt Diamondback, BUT, its already "there" in a sense.
For a gun to reach the Python's status in today's world, it would logically have to go toe to toe, so to speak, with all of the traits that make the Python what it is today. There really isn't a pistol that has a similiar story to the Python. Some revolvers such as the Registered Magnum, the Colt SAA, etc are also very legendary, but they have been for a long time. The "next" Python would have to be a gun that doesn't have a lot of status at this time, but could down the road attain a lot of status. I can't think of anything.
This topic reminds me of a fellow collector friend of mine who has said "Japanese Nambus will be the next lugers..." and well, lets just say the Nambu is hardly in the same sentence. There really isn't another "luger" and there really can't be, when you think about it. I told him, after he said it to me enough for me to be annoyed, that the P38 has a much better chance to approach "luger status" but even then, the luger has a few things about it that can never be taken away, IE how early the design was, it was offered up with the 9mm luger caliber itself, service in two world wars, its unique action, etc. Of course the P38 has a great history itself, but I'm not sure there could ever be another "luger" although the 1911, certainly has a very admirable history itself.