Developments in the saga of the sale of the Boston Arena took an apparently favorable turn yesterday, with the announcement of the possibility that the Metropolitan District Commission might purchase the sports palace for use by Boston school and college athletes.

A bill filed in the Massachusetts Legislature would direct the M.D.C. to provide an arena, acquired by "purchase, construction, and/or gift."

Presumably, the bill follows the lead of a recent suggestion by Boston Mayor John B. Hynes, who thought local communities might purchase and pay for the upkeep of the Arena in proportion to their size. The M.D.C. handles just such functions, with Boston itself footing the major bills.

The Arena, however, has already been "sold"; it is scheduled to be turned over to a group of business men, and to be converted to factory space after March 15.

The quesiton of whether the Arena can actually be bought by the M.D.C. is, therefore, pressing. The question of whether the Legislature will pass the directive is even more pressing.

Arena and Boston Garden manager Walter Brown has stressed the fact that the St. Botolph Street property has been disposed of. It is known, however, that the Arena has been offered to the city in the past for less than the $400,000 the purchasers are paying.

All sports contracts, including Harvard hockey practice and games, expire before the March 15 date.