In a sense, this is right. Our ordinary conciousness consists largely of projections into the past, future and hypothetical situations. As the illustration above suggests, in this state out attention is largely temporal (forwards and backwards in time), leaving very little mental bandwith for awareness of the reality of what is actually occurring. Not only that, but (given the current impossibility of time travel) experiencing the past and future is impossible, so all of this awareness is virtual - it is hypothesised from what is going on now, such as memories and predictions based on deduction, intuition and experience. We take these abstractions for truth or reality and the process of projection and identification with past and future events causes us to see our life in terms of continuous existence. We wonder whether this continuity will cease with physical death or continue into an afterlife.
When we do zazen or similar meditation, this virtual activity quietens down and we become aware of what is actually going on. I don't mean that we suddenly gain special access to what is thought of as 'objective reality' or Kantian 'things-in-themselves'. But we experience the events of our life unmediated by thought - we experience the sounds of our breathing or sounds from outside directly, in all it's uniqueness and familiarity and it's indescribable complexity. We can feel the causal reverberations of the universe. We can't find anything (other than convention) to distinguish between the events in 'ourselves' from those 'outside'. Seeing our memories as experiences that literally 'we' did or didn't have no longer seems to mean much. The idea of annihilation or continuity into afterlife no longer seem to mean much. Instead memories and anticipations are just mental events occuring now - one more aspect of the relentless surge of change without real begining and end, which is the real nature of this life. To experience this is to experience Ku, Sunyata, emptiness.
I used to think that the aim of Zen was to exist in this state permenantly. However, this is impractical - we need memory and anticipation to survive. Also to see this state as real and the ordinary state as false or inferior is to create one more duality and duality is the activity of samsara, the deluded mind. The true aim of Zen as I understand it, is to find this emptiness in meditation and contemplation and to realise that when we meditate we are not creating emptiness nor are we moving from non-emptiness to emptiness - rather, we are paying attention to the emptiness which is the actual nature of all of our existence, whatever we are doing, whatever our state of mind. There never was a continuous self, nor continuous entities of any sort. There is only a vast rippling matrix of interdependent cause and effect. Looking inwards or outwards we can find no continuity. What we thought was the continuous existence of ourselves is really change. Whether we realise it or not existence is empty of self - whether we are in a 'zen state' or an 'ordinary state' there is no continuous self. We don't need to be in a special state to make emptiness real. The only thing that makes a difference in this respect is seeing the nature of things or not and how this affects our experience of living. In this sense ordinary mind and zen mind are already one, samsara and nirvana are not different.