A customer has had a defined contribution plan for a while, participation is open to all employees if they work the threshold 1000 hours. Now, the customer wants to cut back on who can participate based on their job types. The customer understands it can't change the rules for present employees. But for John Doe who is hired next year in a job classification that will be cut, I'm not sure how the plan can be revised to maintain the present participants and prospectively cut job classes. I've drafted a web of the 1,000 Hour Rule and its implications if not followed; I've looked at non-discrimination rules; I've looked at the general plan amendment rules.
I'm stumped. What other rules should I read to figure out this goal? So far it looks like the plan cannot be amended to prohibit future participants based on their job classification, but I have to imagine there is some mechanism that allows it.