Only if the approval/development process from patent to market is already eating up 90% of the 20 year patent protection. Companies don't look that far into the future. A 30 year patent creates a profit incentive that will only benefit the company two CEOs and three changes of management in the future.
For a profitable cash flow, the return needs to be huge and far more immediate. Not trickled in over 30 years. It needs to pour in over 5 years or 10 years at most. This gives sufficient capital return and cash flow to fund the next development. If you make the patent last 30 years of even 100 years, then the company might make one drug if you're lucky and milk the profitability over the long term. In the short term, the returns are still too small to re-invest or barely pay back the interest component of the upfront NRE loans. The company is still better off using that upfront capital to invest in a higher return product even if that higher return lasts for a shorter period of time.
Lets say you have $1M to invest and there is a company that is guaranteed to return a net profit of 5%/yr for the next 30 years, and another company that is little more risky but will likely return 25%/yr for 5 years. Even though it might seems like the end result of 5%*30 is higher, it isn't. After 5 years you now have a bigger pool of money to re-invest in other higher return ventures. Obviously if you have unlimited money you can do both. But, there are far more potential high return drug ideas to develop than there is accessible money.
The real problem is why does it take $1B+ to bring an antibiotic to market. Even Penicillin would not exist if it cost that much (in time adjusted currency) to get it off the ground. The reason is that $1B+ is not the actual cost of development, but also the amortised cost of all the failed drug developments/approvals (using hollywood style accounting). The approvals process is also onerous (in both cost and time), along with the corporate culture of huge marketing budgets, political lobbying, and top heavy running costs.
If you like the idea of a regulatory solution, then other incentives would be far more beneficial to the end goal. Such as making all drug approvals subject to audited evidence that some percentage (e.g. 50%) of general drug research expenditure is also made in particular classes of lower return antibiotics, or financial/tax incentives for brining a functional antibiotic to market. Obviously a lot of good possibilities, but I highly doubt that a 30yr monopoly on a low yield investment is one of them.
BTW, the above reasoning applies to patents in general, and why I personally believe that patent publication should be immediate and the duration should be industry specific. And along with a ridiculously low bar of 'inventiveness', 20yrs is too long in most (if not all) industries.