The thought that doping is threatening international sport seems off-base.
Many spectators want to see bigger, stronger athletes performing super-human feats of strength and endurance. Many of those spectators don't give a hoot one way or the other about doping as long as the show is good.
The WWF (later WWE) is a perfect example of this. The "sport" is little more than a well-packaged circus act whose performers are so 'roided up that they look more like cartoon super-heroes than actual people. Calling pro wrestling a sport is a stretch - I agree - but the marketability of athletic entertainment reached a pinnacle (or depth depending on your point of view) with that organization.
People like to see athletes break records (i.e. the home-run race between Sosa, MacGuire, and Bonds). Record breakers fill stadiums and coffers.
The increase in revenue for cycling in the USA prior to Lance was not enough to support a single ProTour level team with any stability. After LA, there were several ProTour teams either based in the USA or with a US company as the title sponsor.
Unfortunately, the fact is that doping helps make athletes perform better. And, spectators, fans, and sponsors want to see athletes performing better. Performance pays the bills.
Ethically, I am rigorously opposed to doping. Financially, I find it difficult to imagine it ever going away.