If the plan termination is in connection with a 410(b)(6)(C) transaction or the employer incurs a substantial business hardship, I'm not seeing an advanced notice requirement. Here is a description from the preamble to the final regs.
QUOTE
The final regulations adopt the exceptions to this 12-month rule that were set forth in the proposed regulations. Thus, a section 401(k) safe harbor plan could have a short plan year in the year the plan terminates, provided the plan termination is in connection with a merger or acquisition involving the employer, or the employer incurs a substantial business hardship comparable to a substantial business hardship described in section 412(d). A section 401(k) safe harbor plan could also have a short plan year in the year the plan terminates (without regard to the reason for the termination or the financial condition of the employer) if the employer makes the safe harbor contributions for the short year, employees are provided notice of the change, and the plan passes the ADP test. In either case, the employer must make the safe harbor contributions through the date of plan termination.
Of course, in your situation, today is the last day of the plan year. I don't see anything that requires advanced notice to terminate on the last day of the regular plan year, either. If the plan document still has the SH provisions in effect on July 1, then you would be under the mid-year termination rules.