I doubt a Communist Vietnam that remains divided would implement the same reforms as OTL.
I think there would be a very similar reform package.
If they have the same kind of economic crisis (and why wouldn't they?) why wouldn't they reform? If they don't, their economy collapses.
When Doi Moi was implemented, their exports were only half of their imports. So they were running out of cash to feed their people. Economic growth had stalled. And inflation was 700%. Financial subsidies from Moscow was running down as the Soviets had their own problems. Furthermore, the Vietnamese noted they were falling behind their regional neighbors.
They really don't have an alternative at that point unless they want the end of their regime.
If they don't reform, the likely end was for North Vietnam to collapse and be taken over by the South, or to bunker down like the Kims did in North Korea and starve their own people to death. However, geography would hurt North Vietnam here. North Korea was isolated on a peninsula. It only had to guard the DMZ and the Yalu River. North Vietnam has LONG borders with multiple countries. A Juche type scenario would see a flood of refugees enter Laos and then South Vietnam looking for food. They couldn't keep their nation in Prison like the Kims did.