H3BO3 is not a traditional acid, in that it does not deprotonate to produce H+. In aqueous solutions, H3BO3 attracts a water molecule, bonds to its oxygen and produces H3O+ via deprotonation of the newly bonded water molecule. The acid in this case is actually HB(OH)4. In anhydrous conditions it acts as an electron acceptor, not necessarily an H+ donor. Due to its character as a lewis acid, I would expect B(OH)3 to pick up the OH- from KOH, forming K+ B(OH)4- as a salt. The presence of water as a solvent or otherwise may affect the products of the reaction.