Here's how Senate control would have changed over the last decade if DC had been a state:
2010: D (IRL) --> D (with DC)
2012: D --> D
2014: R --> R
2016: R --> R
2018: R --> R
2020: D --> D

Here's how Senate control would have changed over the last decade if DC and Puerto Rico had been states:
2010: D (IRL) --> D (with DC+PR)
2012: D --> D
2014: R --> R
2016: R --> R
2018: R --> R
2020: D --> D
*ALSEN in 2017 is an interesting side-story

If PR/AL were states, then the Doug Jones race in 2017 would have flipped Senate control (which the GOP would win back in 2018), though there's a distinct possibility that Jones wouldn't have won if Senate control was on the line

Donald Trump would still win the presidency in 2016 https://twitter.com/JgRestore/status/1347925782790885376?s=20

the point isn't that there would be no consequence to up to four new Democratic Senators, it's that it wouldn't fundamentally change the balance of power--as many assume or assert https://twitter.com/brent_winslow/status/1347930068945928192?s=20