Christianity has been going for 20 centuries. And Judaism for even longer.
2000 years is a blink of an eye, in historical terms. The idea that a (relatively very young) religion is immortal just because it's lasted a mere couple of millennia is simply not based on logic. Most now-dead ancient religions lasted far longer than Christianity.
The religion of Ancient Egypt lasted for at least three and a half thousand years, that's nearly twice as long as Christianity.
Many indigenous Mesoamerican religions were practised for thousands of years.
Mithraism lasted probably three or four thousand years, if not longer.
Judaism is sort of the exception since Judaism is a religion of the diaspora; most ancient religions died because they came from a specific country or region, and the religion died when that country was conquered or fell. Whereas Jews did not even have their own country at all until 1948 and most Jews don't live in Israel. Plus Judaism is considered an ethnicity as well as a religion, and there are very concerted efforts made to ensure the continued existence of Judaism and to protect against dangers. But Judaism will either die or evolve into something else too, in the passage of time.
All religions eventually die out, or evolve and aggregate (as older forms of paganism did) into new religions.
The Bible itself has the beginning, the middle and the end. So no, Christianity and Judaism will not end.
Those two sentences do not follow on from each other. The Bible is just a book, a book lots of people have projected great meaning onto, but still just a book. Most books have a beginning, middle and end, that's literally the definition of a book. You think dead religions didn't also have their own religious texts?
Christianity might still exist in two thousand years. It's very unlikely but religions have lasted that long before. In ten thousand years? Not a chance.