That's a bit of a fantasy, isn't it? Pharma companies don't re-invent the same wheel: even in cases where they're pursuing similar avenues of research, the drugs being developed share sometimes significant differences (and in many cases, even insignificant differences can later be found to be more significant than first believed). Even if companies were somehow able to collaborate without any problem, the end result would be a decrease in the number of medications brought to market. Instead of multiple therapies that doctors can use to tailor to their individual patients, they'll get one that works for the majority of cases and woe be to anyone who falls outside the bell curve. The developing crisis with antibiotic-resistant strains is a perfect example of the sort of problems that arise from such short-sightedness.

But that's a scenario based on your idea being feasible. The far more likely scenario is an even more brutal and unethical market, where companies use controlled distribution (such as with Daraprim) to prevent generics from being tested, and thus, being brought to market. Why? Because without patents, even that limited initial window for drug companies to earn back R&D costs--along with supporting the sunk R&D costs wrapped up in the larger number of drugs the fail to bring to market--exists only so long as the manufacturer is able to use whatever force is available to it it to stop generics from being produced. Far from cooperating with one another, pharmaceutical companies would have every additional incentive to stab each other in the back. Instead of skirmishes like you have now, you'd have a war to the knife.

It's easy to look at problems with the current patent system and think that they'd all magically be fixed by getting rid of them. But unintended consequences are still consequences.