SpaceX now routinely recovers and re-uses its Falcon 9 boosters by either flying them back to land or a drone ship in the Atlantic Ocean. For Falcon Heavy, SpaceX plans to recover all three of the Falcon Heavy's booster rockets. All three! The two side boosters will return to Cape Canaveral, and the center core will land on the drone ship Of Course I Still Love You.
There are a variety of possible outcomes for the demo flight: complete success, partial success, total disaster, loss of one or more boosters attempting to return to Earth, and the usual litany of everything that can go wrong during a rocket launch. In any case, it will be quite a thing to see.
If things go completely awry, it's unclear how soon SpaceX would continue marching through its Falcon Heavy manifest. Ultimately the big rocket is an interim solution; SpaceX plans to merge both the Falcon 9 and Falcon Heavy into a single, larger vehicle called BFR (Big Falcon Rocket, if you want to avoid expletives).
The company has already bounced back from two operational failures of its workhorse Falcon 9 rocket, so a disaster for this Falcon Heavy demonstration flight shouldn't be a huge setback—especially considering the low expectations Musk set. The only scenario that could cause the company significant problems would be if the Heavy badly damages the launch infrastructure at pad 39A and delays NASA's commercial crew program.
As far as I know, there's never been a rocket launch where the vehicle provider openly told the public there was a high chance things might end catastrophically. Succeed or fail, the demo flight is sure to be a blast!
