Subject to the authority conferred upon the Secretary of the Interior by this section, the land districts and land offices existing in Alaska on October 9, 1942 are continued. The Secretary of the Interior is authorized and empowered in his discretion to change the boundaries of, or discontinue, any land district in Alaska, and in lieu thereof to designate such land district, or land region, as, in his opinion, is necessary for the transaction of the business relating to the public lands in the Territory and to designate or change the location of any land office for such land district or land region.