Most importantly, the plans are structurally different. Contributions to TRS and ERS go into the State's pot and do not provide an additional benefit to an employee's pension. Eliminating the required contribution would make this money subject to Federal taxes. Most changes would require changes in the plan's position within the tax laws. Understand that nothing is simple or easy when it comes to dealing with pension matters and tax laws.
Nothing is precluded, just as nothing is guaranteed.
You said there were other changes in the pension laws. The Legislature also enacted a permanent cost-of living adjustment for ERS and TRS members who are already retired and future retirees as well. In addition, the Legislature reenacted the early retirement incentive plan. Yes, just about identical. You must be at least 50 years of age with a minimum of ten years of service as of the date of retirement.