If you and your parent's other heirs (if any) would be interested in owning the company after your parents pass away, then you could have them place the rental property into a business structure which has shares - either a corporation or perhaps some sort of partnership. Each state has somewhat different types of business structures, so check with the Louisiana secretary of state's office to see what your options might be. It may already be in a suitable structure.
Then, each tax year they could gift you and each of the other heirs enough shares to equal $15,000. $15K per year can be excluded from gift taxes and estate taxes. Furthermore, there are no capital gains - you and the other heirs get the original cost basis and holding period.
If the commercial rental property is worth a really whole lot of money (multiple $M) and/or there aren't that many heirs, then this strategy won't make much of a dent in the problem. In that scenario, if your last surviving parent dies at an inopportune time, you might have to sell the property to pay the estate taxes. If this is a concern, you may want to look into an ILIT to buy a second-to-die policy on your parents for enough to cover the estate taxes.
After they pass away, if you and the other heirs have managed to retain ownership of the rental property through this strategy, you could look into doing a 1031 exchange into rental property that is more to your liking (an apartment complex, individual rentals, a couple of duplexes or 4-plexes).
To do this will require spending some money on a CPA and maybe consulting an attorney to get the business structure set up properly.