I would argue that history suggests this is likely. The dopers have substantially more financial resources than the testers. EPO is a great example. It was widely used in cycling for almost 10 years before tests were developed. It was pretty much a miracle drug from a performance standpoint and undetectable. The very few cyclists that tried to blow the whistle were run out of the sport. Similarly, blood doping was widely used for a decade after the EPO test was developed and no one ratted out the teams doing it until USADA brought the hammer down on Armstrong.

It’s also worth thinking about the incentives to test and catch cheaters. Do the organizers of the Tour de France really want to bust the biggest names in the sport? That would destroy their livelihood. Do the national anti-doping authorities want the athletes from their country busted (look how many national antidopingborgs have successfully appealed adverse rulings through CAS)? It’s in everyone’s best interest to bust a low level doper here and there to make it look like they are watching but to ignore the big names that fans are coming to see. All of this is also why motor doping is unlikely. Motor doping leaves incontrovertible evidence of cheating. Positive drug tests can always be challenged as either inaccurate testing or unintentional contamination.