There is a curious but persistent belief amongst some Buddhists that the Dhamma will soon disappear. Although this belief is usually in the background, it comes to the fore at those times when there is a heightened awareness of the many inevitable inadequacies in Buddhist institutions. But is there any truth in this belief? Firstly we must be clear about what we mean by `Dhamma'. The Dhamma is (1) the truth about the nature of reality, it is (2) that truth as realized and described by the Buddha in his many discourses and dialogues, and it is (3) the applying and practising of that truth by those who call themselves Buddhists. In this first sense the Dhamma cannot disappear any more than space, energy or time can. For as long as anything exists, Dhamma exists because Dhamma is the nature of reality. In the second and third sense, the Dhamma will eventually disappear because all compounded things (saïkhàra), including the Buddha's words and human understanding of them, are subject to change (anicca). Having disappeared, it will sooner or later be rediscovered by a new Buddha and proclaimed to the world again. The Buddha of the next era will be named Maitreya.
So when will the Dhamma in these last two senses be no more? Once the Buddha was asked what would lead to `the obscuration and disappearance of the good Dhamma'. He replied that there would be two things. `When the letters are wrongly pronounced and there is wrong interpretation of their meaning. For when the pronunciation is wrong, the interpretation will also be wrong' (A.I,59). Here the Buddha was referring to his words as they were remembered by his immediate disciples, later committed to writing and as we have them today in the Tipiñaka. In this sense, the Dhamma is in no danger of disappearing. In fact, with printing, books and electronic media it has never before been more secure, more easily available and more widely read.
On another occasion someone put a similar question to the Buddha. `What is the cause, what is the reason, why the good Dhamma does not last long after the Tathàgata has attained final nirvàõa?' The Buddha replied:`It is because the four foundations of mindfulness are not developed and cultivated that the good Dhamma will not last long' (S.V,174). Here the Buddha was saying that for as long as people continue to purify and clarify their minds through meditation the Dhamma will endure. On this same issue the Buddha also said: `Earth, water, fire or wind cannot make the good Dhamma disappear. But foolish people right here will make it disappear' (S.II,224).
So this is the answer to the question of how long the Dhamma will last. The Dhamma does not have any set lifespan nor is it predetermined to disappear at any particular time. It will endure and flourish for as long as those who call themselves Buddhists practise it with commitment, sincerity, understanding and love and `foolish people' (moghà purisà) are a minority.