Vis. masternode tiers, it's not a priority at the moment: right now they're concentrating on delivering the core platform. However, they certainly know that the community want lower collateral masternodes and as far as I know, they have committed to delivering 10k Strat masternodes. I know this has been said for over a year now, but we won't let up until they've been delivered.
As for the cold staking, it will be a feature of the C# Full Node, which will be coming in the next few weeks. It'll be available in the C# Full Node GUI, which is the wallet called Stratis Core (also coming this month). The only thing to bear in mind is that Cold Staking needs to be activated. So it's coming with the C# Full Node BUT it will only be available once 95% of the staking . network is staking using the C# Full Node. This is because cold staking requires a soft fork to activate and so for security reasons we need to have the significant majority of block producers using the C# Full Node client.
So the ETA depends on how quickly people migrate to the new FN.