Mikhail Gorbachev may not be around as Soviet leader long enough to carry out the treaty he signed at the summit last week. That's the word from the Central Intelligence Agency and other Kremlin watchers. Gorbachev is on shaky ground. His reform plans have so unsettled the Soviet elite that an ouster or even an untimely death is possible before the end of 1988.

So far, the CIA thinks Gorbachev is the genuine article and the glasnost, or openness, he advocates is real. So is the perestroika, the Russian word for "restructuring" and the title of his new book. In the kind of openness rarely seen in a Soviet official, Gorbachev calls his predecessors "stone-faced sphinxes" who indulge in "grandiloquent twaddle {and} unwarranted splendor, abstract slogans, and recurrences of pompous ostentation."

The trouble is, some of those "stone-faced sphinxes" are still around. Gorbachev is threatening their cushy lives with his perestroika, which is nothing less than a reordering of the power elite. The top rung of the Soviet class system -- the nomenklatura -- numbers 600,000 to 800,000 people. It is those people who threaten Gorbachev's continued power, if not his life.

One CIA analyst said of the Soviet upper class: "They send their kids to school in Switzerland. They shop in special shops in Russia . . . . They vacation where they choose. And they are livid about Gorbachev's economic and other reforms."

Nothing unnerves a socialist like the threat of pure socialism -- the spreading around of wealth and power. The most serious sign that the elite are still in power is the ouster last month by the Communist Party Central Committee of Boris Yeltsin as head of the Moscow party. Yeltsin, a Gorbachev ally, bad-mouthed conservative party officials for hindering the leader's reforms.

Some CIA analysts say Gorbachev leans too heavily on the KGB state security forces, one of the three pillars of power in the Soviet Union. The others are the Politburo (political leadership) and the Red Army. The KGB spreads disinformation about Politburo members before Gorbachev deposes them. Gorbachev leaves the KGB out when he talks of reform. Its internal and international actions continue unchecked.

Last June, Gorbachev gave the KGB a foothold in the Red Army. After the audacious flight of West German Mathias Rust, who piloted a single-engine Cessna from Helsinki to Red Square, Gorbachev had an excuse to fire 75-year-old Defense Minister Sergei Sokolov and subordinates.

Then, Gorbachev chose Gen. Dimitri Yazov, the deputy defense minister of personnel, to replace Sokolov. Of all the positions in the military, CIA analysts point out, this is the one in tight cooperation with the KGB. In fact, it is often held by a KGB official in military uniform.

"The KGB has a deal with the army that they have total access to personnel files," one source said. "They are intrusive in the military, and the personnel man is their springboard into it."

Whether the KGB's support is powerful enough to counter the anger of the nomenklatura and keep Gorbachev in power is anyone's guess. But several CIA analysts agreed that if Gorbachev is not deposed in 1988, he may be at the top for years.