Every day that goes by, we get more data and our projections gain greater accuracy. It is definitely too early to discuss server merges, character transfers, etc. We will obviously do whatever we need to do to ensure a good experience, but it is much too early to discuss those options.
To answer the OP: regardless of server populations, faction imbalances are definitely a reality and we've always expected as much. Our contention system is designed to tolerate such imbalances, although at extremes anything can break down. For quite a while we have planned to implement measures to give underdog factions a boost, and that work is being done now. When it's ready we'll explain it in a devlog.