"And in that time of the people with an eighty thousand-year life-span, there will arise in the world a Blessed Lord, an Arahant fully-enlightened Buddha named Metteyya, endowed with wisdom and conduct, a Well-Farer, Knower of the worlds, incomparable Trainer of men to be tamed, Teacher of gods and humans, enlightened and blessed, just as I am now. He will thoroughly know by his own super-knowledge, and proclaim, this universe with its devas and maras and Brahmas, its ascetics and Brahmins, and this generation with its princes and people, just as I do now. He will teach the Dhamma, lovely in its beginning, lovely in its middle, lovely in its ending, in the spirit and in the letter, and proclaim, just as I do now, the holy life in its fullness and purity. He will be attended by a company of thousands of monks, just as I am attended by a company of hundreds.
So we can see here that we have to wait for a very very long time before the next Buddha arrives. Bodhisattva Metteyya is now in Tusita heaven...waiting for the ripe conditions to be a Buddha. There are many teachers who say that they are Metteyya but just think about the above paragraph. For us to understand this we need to know about the evolution of human lifespan through the years....now we are in the declining phase till we reach rockbottom then the human lifespan will increase again......please read further about this if you are interested. We need to ask ourselves what are the qualities of a Buddha, do they fulfill all the qualities of a Buddha?
Ajahn Chah probably meant that we need to practise and not just loaf around waiting for the next Buddha....He is skillful in teaching.