Here we go again...
A220-500's lack of TCON range won't be a deal breaker if the intent is to replace their existing A320 fleet in circa 2030. -500 shares the same crew pool and hopefully the same for parts and maintenance (likely but not guaranteed), it's no different than buying more -300 if the potential revenue it can generate makes up the difference in the extra capex.

Some current AC A320 routes I could found at a glance;

Perfectly within range:
YVR-YLWY
VR-YYC
YVR-YEG
YVR-YWG
YVR-LAS
YVR-PSP
YVR-ORD

YUL-YWG
YUL-MIA

YOW-YYC

YYZ-YOW
YYZ-YUL
YYZ-YQB
YYZ-YHZ
YYZ-YYT
YYZ-YWG
YYZ-YQR
YYZ-YYC
YYZ-YEG
YYZ-YMM
YYZ-LGA
YYZ-PBI

Stretching the limit but probably okay:
YVR-IAH

Probably out of range:
YYZ-YVR (Plenty of XLR available to fly this route in the future)
YYZ-YYJ (Seems like an A220-300 sized route)
YYZ-LAX (Plenty of XLR available to fly this route in the future)
YWG-CUN (Should be flown by Rouge anyway)


The question we should be asking isn't the range. It's if AC need to fill the gap between A220-300 and MAX/A321.

I certainly see the extra 4 Business class seat on the -500 would be helpful on some days and time between YYZ-YOW.