Thanks for sharing this useful link. Exactly how does staking difficulty work? The more difficultly there is on the network, the less staking reward you will get, or is the reward based on stake weight? Sorry for asking, I'm very familiar with coin staking.
I find it useful to view things in terms of proportion when it comes to POS, especially POS 2.0. View things in terms of percentages rather than raw absolute numbers.
The answer to your question is yes, when staking difficulty rises you will get lower rewards. Not because the block reward of 20,000 changes, but because there is more competition on the network and you represent a smaller percentage of the total coins staking.
There are 1350 blocks mined per day, each rewarding 20,000 LDOGE. If 100% of all LDOGE is being staked 24/7 and you are staking 1% of all LDOGE, you should expect to hit on average 13.5 blocks per day. BUT we know not 100% of all coins will ever be staking 24/7. If only 50% of the total coins are staking every day rather than 100% and you stake your same 1% of coins 24/7, you should expect to get 2% of new blocks or an average of 27 blocks per day.
By counting the number of blocks I mined in the past 24 hours, comparing it to the number of blocks I should expect to mine if 100% of LDOGE were being staked, and doing some quick and dirty math I can roughly estimate that about 63% of all LDOGE was actively staking in the last 24 hours.
So, if you want to get an idea of how many coins you can expect per day, use this formula IF you will be able to stake 24/7.
((Your total # of LDOGE) / (The total # of LDOGE in existence, found by entering 'getinfo' in the console in case you weren't aware)) x 1350 x 20000 x 1.582The 1.582 represents a multiplier that reflects my rough estimate of 63% of coins actively staking.
Cheers 
