The only thing I can think of is that if you downgraded and left a points balance, you can't use them for partner transfers. What are the points worth to you on United vs. if they were used as cash back redemption on the Freedom?
This one could be tricky because "points" value can change dramatically and the travel industry is in a period of major realignment. Who knows what points will be worth in the future?
That said, one option would be to simply cash them out for $1800 at 0.01 ccp and put it into a high yield savings for spending wherever and whenever you do decide to travel. Puts you totally in control and insulates you from any point value loss.
Transferring to United would be an acceptable option also if you want to retain the potential for a higher return via travel redemption.
You can, however, transfer those CSR UR points over to either the Freedom or Freedom Unlimited before you close or downgrade the CSR. It's easy to move points and I do it all the time. (Top menu of UR; click "more" and "combine points".) Later, you could just transfer back to the (new) CSP or CSR once you do reopen it.
If at signing, I had intended to keep the CSR as a long term rewards card, one bad year where I didn't feel I got my money's worth wouldn't ruin my feelings toward the card or its benefits.
If I had planned on churning the card and just wanted the SUB, and wanted to dump the card the second it stopped returning my AF in rewards, then go right ahead.
I run about $20-25k through my CSR annually, and I feel I'd break even on a lesser AF / lesser rewards card. It just wouldn't matter too much, mathematically. So long as my new CL wasn't impacted, I wouldn't feel cheated out of anything.
I am somewhat vain and love plunking down a metal card, even just seeing it in my wallet. I'm big on the tactile feel of a card, the heft and design. My advice would be do what takes care of you, so long as you're under 5/24, and low INQ. Always keep your profile ready to apply 
Let us all know what you decide!
@Anonymous I hardly feel like I'm churning the card, don't make me feel so guilty! 
I've had it for a solid 4 years & paid three AFs.
I did sign up with the intention of it being a long term travel card but my spend pattern and travel plans are going to be thrown off for a minimum of 2 years, due to the pandemic & a home purchase, not just one bad year.
I share your sentiment on the metal card feel and I've been proud to have the C$R and take advantage of the benefits over the years. I've used the Primary Rental Car Insurance several times on vacation, utilized the Priority Pass lounges when I've traveled internationally, Global Entry, etc. But $550 is large fee if you're not utilizing the benefits for a while.
Not sure if this was suggested, but what about just keeping the points and downgrading. In the future, if/when travel opens up again, you can upgrade back to the CSR and use the points as is.
[2/2019]
180,000 UR is a large value. I would not be too quick to just give them to United.
I would transfer them into the CFU as a least worst option. Worst case there, you redeem them at 1c through Chase.
Best case, you apply for a new CSR in 2021 for the updated SUB, pull the UR back to CSR and do some awesome redemption with the ~250,000 UR.
