It was quite possible that after Mao's death, no clear leader emerges, factional infighting spirals out of control, and as a result China returns to the 1920s with zillions of warlords and a dozen foreign powers intervening in some form.
Something like 1989 Czechoslovakia? Not a chance. The Party was literally the only organization in the entire country, and if anything the peasants (who were 90% of the population) wanted merely a strong and stable government which would provide food. Deng Xiaoping promised and delivered on that.
The protests in 1989 started primarily because of discontent over Party apparatchiks taking advantage of the half-market economy to enrich themselves, and was only later hijacked by some students calling for much more subversive goals. When everyone is equally impoverished, where is the impetus to voice discontent?
On that note, many of the Tiananmen Square student protest leaders who fled the country have turned to be complete and utter scumbags, but that's for another day.