Can the team make an announcement when masternode owners have to register their masternode? Just to remind masternodes when it's time.
Yes. The Masternode update is effectually a HEAT hard fork at the same time, so all nodes on the network must update to version 3.0.0 or later from
https://github.com/Heat-Ledger-Ltd/heatledger to not be blacklisted from block 2700000 onwards. We'll be notifying this on our available channels.