It’s impossible to know for sure. But the choice of Gorbachev was a natural result of trends in the Soviet Union and it’s hard to say how it could have been different.
The “old guard” was the generation that had survived the Stalin era and felt that they had to maintain the system to justify the ordeal the USSR had suffered. Hence after some flirtation with reform during the Krushchev era, the Party settled down to the long years of stasis under Brezhnev. But while the Soviet Union appeared strong from the outside, it was facing increasing pressures. The biggest was that economic development in the USSR stagnated after 1970. Essentially, the decades-long policy of industrial development had plateaued out; everything that could be built by fiat, by simply ordering it to be built, had been. At this point there was nothing left to do but to try to run the command economy efficiently and to modernize, and the USSR failed miserably to do so.
Gorbachev was representative of the new blood. The horrors of Stalinism were mercifully history and they were less averse to facing up to the system’s obvious flaws. The only alternative to Gorbachev or someone a lot like him would have been a die-hard neoStalinist movement, and the party leadership knew better than to go down that road.