I think there was no final decision about it. I heard rumors that it would be 50k TOMO but on the homepage they are stating that this is still open and will be decided when the mainnet is live in 2019.
Also there will be a staking mechanism that allows coin holders to vote/ stake for the masternodes of theirs choices and receive proportional revenues.
Why in 2019? By their roadmap mainnet launch in Q4 2018 year. And they didnt make any updates in roadmap and announced as I know.
In Q4 2018 the mainnet will go live using PoA Consensus. in 2019 Consensus will switch from PoA to PoS-Masternodes.
You can read this up in the faq
https://tomochain.com/faq if you click on "How many tokens are needed for masternode?"
Check out page 9 of the linked slideshow
https://www.slideshare.net/LongVuong2/tomochain-introduction