Bitcoin itself won't be taken over/replaced by a different cryptocurrency unless there is some major shift with the cryptosphere or a lot of the fiat financial systems start to move into cryptos and everyone pushes for a new one.

Bitcoin can change and be modified, but there's a very small chance that Bitcoin will be replaced in the foreseeable future.

I can easily believe that bitcoin won't be the one. While the conspiracy three letter agency/bank stuff doesn't turn me on, what could be a more perfect plan than planting the seed, prick the greed of a bunch of fractious techno weenies, let them do all the technical heavy lifting, kill it off themselves and then reap the technical benefits?