Will Buddhism last only 5,000 years after Buddha's Mahaparinirvana? Is there any reference/citation saying that Buddhism or Buddha's teachings will last only 5,000 years after Buddha's Mahaparinirvana? How can this be possible if more people like to learn more about Buddha's teachings and Buddhism? Is there any weak point in Buddhism or Buddha's teachings that it is going to cease to accept and learn any more by people because that particular point is no longer adaptable by current/future generation? It could be related to moral principles, rules, disciplines, as well as concepts and ideas.
In the Vinaya (monk's rules), it is said (somewhere) the Buddha's teachings would last for 500 years (rather than 5,000 years). Many Buddhists claim this did not come true therefore the Vinaya teaching is false, for example:


  The passages surveyed so far help to set into context the prophecy that because an order of bhikkhunīs had come into existence during the
  lifetime of the Buddha, the duration of the teachings will be
  shortened to 500 years (Cv X.1). Now this prophecy is surprising,
  since once would not expect the Buddha to do something which he knew
  in advance would have such an effect. In fact, the prophecy in the way
  it is recorded in the Vinaya has not come true, as after 2,500 years
  the teaching is still in existence. Even the bhikkhunī order was still
  in existence in India in the 8th century and thus more than a 1,000
  years after the time of the Buddha.
  
  Bhikkhu Anālayo


Apparently, this was later altered by the scholar Buddhaghosa to 5,000 years (see here).

However, the majority of Buddhists, including Bhikkhu Anālayo, seem to often interpret many Buddhist teachings in a manner contrary to the original spirit of the teachings (such as, originally, the teachings of the Buddha were to be only accepted upon personal verification rather than through mere faith in unknown things). This seems to make an argument the 500 year prophecy actually came true in respect to the mainstream Buddhist religion. This video seems to make such an argument: The True Dhamma Has Disappeared: Thanissaro Bhikkhu

That being said, the Pali scriptures are mostly still pure so they do continue to exist in their purity. 


  In the course of the future there will be monks who won't listen when discourses that are words of the Tathagata — deep, deep in their
  meaning, transcendent, connected with emptiness — are being recited.
  They won't lend ear, won't set their hearts on knowing them, won't
  regard these teachings as worth grasping or mastering. But they will
  listen when discourses that are literary works — the works of poets,
  elegant in sound, elegant in rhetoric, the work of outsiders, words of
  disciples — are recited. They will lend ear and set their hearts on
  knowing them. They will regard these teachings as worth grasping &amp;
  mastering. In this way the disappearance of the discourses that are
  words of the Tathagata — deep, deep in their meaning, transcendent,
  connected with emptiness — will come about.
  
  Ani Sutta