(a) Any person authorized to acquire property for a particular use by eminent domain may exercise the power of eminent domain to acquire property to be used in the future for that use, but property may be taken for future use only if there is a reasonable probability that its date of use will be within seven years from the date the complaint is filed or within such longer period as is reasonable.
(b) Unless the plaintiff plans that the date of use of property taken will be within seven years from the date the complaint is filed, the complaint, and the resolution of necessity if one is required, shall refer specifically to this section and shall state the estimated date of use.