The Vietnamese are not Chinese. They do not revere the Center, they see no Mandate of Heaven. The bosses cannot get away long with allowing them economic freedoms without the whole kit. The Veecee (the universal Vietnamese term for the government people) think to emulate China in allowing the freedom to get rich and withholding the liberties that threaten their positions but, again, they Vietnamese are not Chinese. Things Communist will fall apart.
I've met several children of Communist Party officials, some here in the States, some in Vietnam.
Those in the States are easily identified because they came here on student visas (only avalable to CP families) and found inventive ways to stay. They're by no means Communists, and they sure as heck don't want to go back until there's some sort of freedom.
Those in VN are ID'd by their odd Aussie English accents. They've also been educated abroad, something only a CP official could afford and swing for the kids.
In neither case do they even minutely believe in Marxism as an ideology, and the CP is seen only as the strange vehicle by which they were granted favors.
Even my Vietnamese USPS mailman believes the CP will throw in the towel the minute the old fogies pass away.