Out of the several provinces which are apparently planned, only Mae Sot make it into the English language press so far - even though The Irrawaddy in their article from June 2007 only mentions half of the plans for the Mae Sot, the upgraded municipality.
The plan, at least as of June 2007, is to create new province named Mae Sot covering the five districts of Tak province which border to Myanmar (Burma) - from north to south these are the districts Tha Song Yang, Mae Ramat, Mae Sot, Phop Phra and Umphang, as depicted in the map. For a better administration, also the creation of three minor districts has been suggested, Ruam Rat Khiri (กิ่งอำเภอรวมราษฎร์คีรี) from Phop Phra, Mongkhon Khiri (กิ่งอำเภอมงคลคีรี) from Mae Sot and Haeng Mai Laeo (กิ่งอำเภอแห่งใหม่แล้ว) from Tha Song Yang. But as all three minor districts aren't named after a subdistrict and the source does not mention it, I cannot say which part of the districts will be split off.
Additionally, the town Mae Sot as the main border crossing to Myanmar is supposed to become a metropolis (มหานคร), which is supposed to be a special administrative area similar to Bangkok and Pattaya, so outside the normal municipal (thesaban) system. But what the differences between this metropolis and a thesaban nakhon are suppose to be - I have no idea. Anyway, this metropolis is planned to cover the subdistricts Mae Sot, Mae Pa and Tha Sai Luat of Mae Sot district. The current town of Mae Sot (เทศบาลเมืองแม่สอด) covers only the subdistrict Mae Sot.
All the above is from an article in Thai newspaper The Manager from May 22 2007. Just one thing the article does not mention - when will that new province become reality?