In every election cycle, there are always folks who the media expects to run and believes they will be a game changer. Sometimes, they don't actually run - look at Collin Powell in 1996. Everyone thought he would be the nominee and had the best chance of being elected President. He never ran. But this is now the third cycle in a row where we've had a candidate who won a lot of attention and was considered to be a game changer, and it never materialized. Fred Thompson was thought to be the conservative alternative to McCain, Romney, and Huckabee in 2007-2008. Rick Perry was thought to be Mitt Romney's biggest obstacle to the nomination in 2011-2012. Now, we have John Kasich.
I always thought Romney was the "conservative" alternate to McCain, and Huckabee was just the SoCon guy. Not counting Thompson since his campaign obviously imploded.