As a side bar; did any of you ever notice just how small the seeds to either of the Sequoias are? It is amazing how very small the beginning of these trees are compared to the size they achieve in the ends of their lives.
I think you'll eventually find out that's not always true. There are many trees (or perhaps it would be more accurate to say, plants that are used for bonsai, since not all are trees) that can survive, even thrive, indoors without dormancy. Just look at the work of Jack Wikle. However, even he states that there are some species that eventually decline and perish if not given suitable dormant periods.
Despite that, I say experiment! Maybe you'll discover a way to make those species work. As for the sequoia, I have no idea how one would fare long term without a dormant period. Might do great, might decline and die after some number of years. Let us know!