Nothing stays in teams forever. The devs make money by releasing crazier and crazier and crazier and crazier Hime, so eventually, everything gets replaced.
Also, if you have 25 Eyes, why do you even bother asking? Just Awaken everything. By the time the next Awakening is out, you'll have made ~3 more Dragon Eyes from events anyway. Assuming that your Union lands in like, top50, which shouldn't be all that hard.