The government of a county and the government of one or more municipalities located therein may be consolidated into a single government which may exercise any and all powers of the county and the several municipalities. The consolidation plan may be proposed only by special law, which shall become effective if approved by vote of the electors of the county, or of the county and municipalities affected, as may be provided in the plan. Consolidation shall not extend the territorial scope of taxation for the payment of pre-existing debt except to areas whose residents receive a benefit from the facility or service for which the indebtedness was incurred.