Within three or four years, Cambridge may be able to boast of one of the nation's most modern cable television systems--perhaps so complex that residents could talk back to the t.v., yet so simple that virtually anyone could gain access to the airways.

Or, perhaps, the whole idea could fall through, a victim of the tax cuts inspired by Proposition 2 1/2 and the technical problems of setting up a t.v. network in a city as old as Cambridge.

The city council's public service subcommittee will address the issue for the first time Wednesday, when it holds an informational meeting on the report of an advisory commission. "We're just going there to answer questions." Joseph Sakey, who headed that commission, said.

But Sakey added that there is one question sure to come up, both at the meeting and throughout the long process of building and licensing a cable system--the commission's controversial proposal that the system be municipally owned.

It would be simpler to grant a city franchise to one of the dozens of companies in the booming cable industry and let them develop and sell the service -- a pattern followed in most American communities with cable.

The desire for high quality programming, and the hope that the system might someday generate profits for Cambridge's debt-plagued city government, however, were prime factors in the decision to recommend city ownership of the plan, Sakey said.

Under the commission's proposal, a city telecommunications authority--as divorced as possible from city politics--would be set up to oversee the operation of the system. It would grant the franchise to a firm agreeing to meet tight specifications, and then monitor the company to assure compliance. Sakey said.

"One reason we want city ownership is for the money--if there is going to be a sports channel or a movie channel, it will probably be pay as you see basis, and we want the city to get the money," he explained.

But before the telecommunications authority can even be set up, Sakey cautions, there are a variety of preliminary steps -- a municipal construction feasibility study, for example, should be done later this winter to see how many of the necessary poles and conduits the city already has in place.

And later, a municipal feasibility study will examine the cost and the practicality of the municipal ownership plan, a relatively untested method of supplying cable service.

City council sources say one objection to the plan will be cost--the passage of Proposition 1 1/2 has lowered bond ratings enough in area cities and towns that it is unlikely Cambridge will be able to afford the high interest rates any capital outlay would require.

But others have suggested that a quasi-independent commission, armed with studies to show the money-making potential of cable t.v. in the city, might be able to float a bond issue of its own and raise the necessary money.

Even if the reports, the licenses and the political dealings take place with unprecedented rapidity, cable t.v. is a few years off--the contracts must be put out for bids, amendments must be accepted, red tape followed and cut. Until some new system is constructed, the city's moratorium on cable t.v. within its borders will continue.