nah the challenger wont replace it. Its not a corvette competitor. Its a retro-musclecar that all the big brands are adding to their lineup. Ford have the stang, chevy will have the camaro, pontiac will hopefully bring out a retro transam and dodge have the challenger.
These retro cars will have a mini horsepower war and eventually saturate the market with stupidly fast modern muscle that is perfectly fine for a guy like me who missed out on the scene the first time round in the 70's.

Vipers ,Vettes, Ford GT's etc are high end luxury cars aimed at taking on the Euro exotica so Dodge will no doubt come up with a new different model.