Accountant wants to dissolve a p.c. but the pension plan is still in existence. There are some issues preventing it from being terminated.

Is there a recent change that allows such pension trusts without sponsors?

Don't know of any changes that sanction a plan without a sponsor, but there are the regs on how to deal with an orphaned plan. For a plan to which no further contributions are being made, the real concern is who will have authority for amending, appointing successor plan administrators, terminating, etc. I've dealt with Form 5310 termination applications with the IRS where we had transferred in formal documentation the sponsorship of the plan from the entity that was dissolved before the plan to one of the owners, personally. After that, the owner that was the successor plan sponsor signed to take the remaining steps of updating and terminating the plan. The IRS did not make any mention of it.