Yes, effective 10.1, ArcSDE is exclusively 64-bit. It's been difficult to find a new 32-bit
computer over the past few years, and it's probably impossible now (non-Intel machines
have been exclusively 64-bit for nearly two decades).
Oracle XE 11 never was supported, and the only reason XE 10 was supported was that it
happened to work (even though no other 10.2.0.1.0 release did)
It will likely be a while before Oracle 12c is supported -- Oracle hasn't released a Windows
version yet.
- V