When (1) a Company is terminating its 401(k) plan and (2) the plan provides that forfeitures (fully forfeited) are used to offset future employer matching contributions - how should such forfeitures be allocated to participants accounts upon such termination (i.e., there are no future contributions to match - so how should the forfeitures be allocated)?

I'd say you need a plan amendment which says that forfeitures can be used to 1) offset plan expenses (legal, accounting, recordkeeping, etc.) related to the termination, and 2) anything left over can be allocated out to participants.