Well considering Miami has stopped offenses with multiple threats in New England and San Diego. I was worried about the Chargers with Tomlinson, Gates, Jackson and Chambers and Sproles and Miami did well. That doesn't mean Miami will play that well next week. But I'm more scared of an offense with many good players on offense and threats and than one really good player. Miami will most likely have Will allen on Johnson, so they should be alright.
If Miami just slows him down a little bit, they should be alright, since they don't really have other threats on offense. There ground game really isn't scary, and their main threat is Johnson, so if they focus to slow down Johnson, they should be alright. Obviously Miami can't take any team lightly, but I feel better with Miami's defense playing the Texans and their one main threat instead of multiple threats like teams like San Diego. It's not like Schaub or Rosenfels are Rivers or Cutler. So Miami definitely has to play well, well this is the NFL after all, but I not scared of Miami's defense handling the Texans offense.