It's a good moment for bitcoin adopters in Vietnam become alert and follow news about it closely in order to keep their funds protected and act before the government tries something against them.
Do you think that there is a chance that the government will try to seize the funds? I don't think that is a possibility, at least not in the near term. But dictatorships don't value personal liberty. So in case the Vietnamese government bans the possession of Bitcoin (which they haven't done so far), then it may be better for the users to stay under the radar for a while. In case they need to urgently cash out their coins, then they can travel to some of the neighboring countries to do that. Overall impact on the market will be limited, because of the small size of the Vietnamese market.
To have a plan B in case of emergency is a good idea, like a triggered migration to a friendly bitcoin country if necessary.