I can see where you're coming from and I suppose there is really no way to know if this game's playerbase will last.
However there are a couple of things that give me hope that the numbers will steady or even increase:
- The first thing is modding support. Give any game modding support and it can last for a long time. Do you really thing Arma 3 would have as many players as it does without modding support? DayZ on the new Enfusion engine with modding support, I can just imagine how many modders will come from arma 3 to make mods for DayZ.
- The second thing is the Enfusion engine. Well, not the engine really but the modules that come with it. A new animation system, a new player controller. Both which will not only bring their own changes, but will open the flood gates for all the content that has been stuck behind these modules. A change that could be potentially so big that some of the devs have referenced it as a DayZ 2.0.
Yeah, we don't know if the players will come back. But I have hope.