Nothing inherently wrong with Sheppard having more capacity than Eglinton. Yes, Eglinton is closer to downtown, but also closer to the competing Line 2. Furthermore, the demand level partly depends on the structure of feeder routes. It is possible to shift a portion of the demand from Eglinton to Sheppard, and thus delay the moment when Eglinton runs over capacity.
I am sorry, Sheppard is a full 6 km north of Eglinton, whereas Eglinton is 4 km from downtown/Bloor.
https://en.wikipedia.org/wiki/Downtown_Toronto
There is no way Sheppard could shift any statistically significant amount of demand from Eglinton and vice versa. Are you suggesting that densification and development be shifted north to Sheppard instead of Eglinton? That is the only way that would make sense, even then there are just too many jobs downtown. Also, the 401 basically cannot be widened in most of North York any more, so densifying Sheppard without a much more robust rapid transit (2-3 times larger) and/or RER system would be disastrous for road congestion. And our government(s) clearly can't afford much more subway anytime soon. IMO This would be a colossal mistake in urban planning.
In a more ideal case, Toronto's density should roughly radiate outwards from downtown, gradually declining the further you get, with the exception of high density nodes / secondary CBDs (Midtown, North York, Vaughan, Mississauga, etc...). Eglinton is the first major east-west road that crosses the Don River/valley north of Bloor. It getting a subway before a westward Sheppard extension should've been a no-brainer. And citing demand projections from highly suspect studies done by Metrolinx that ignored light automated metro for Eglinton to make sure LRT was chosen is just confirmation bias, same as Metrolinx's confirmation bias. Any serious *transit city* is not going to relegate the foremost east-west corridor outside of downtown to 15,000 pphpd (doubtful crush load on an LRT), or even the delusional 22,500 pphpd that some people might cite.
It's crazy how demonized some of us were for having the audacity to say that Eglinton (and Sheppard East) should have been a subway and that they cooked the numbers (Neptis) to make sure LRT won over subway while excluding Skytrain/OL technology from the studies.
How the table have turned today - looks like this line will have the same issues as O-Train.
Toronto is uniquely privileged to have an excellent grid system, density along long linear corridors and a few nodes, perfect for subway with stop distances >1km. Not to mention the linear density along the lake west of Toronto that is perfect for RER-style regional rail. And yet somehow we screwed up multiple critical transit projects in the last decade (Line 6 is not critical, it's not even the busiest bus corridor post-covid).
I am calling it, we'll regret this easily within my lifetime. The lack of route capacity on Eglinton will inevitably force densification and development elsewhere. Best case, adjcaent corridors like St. Clair and Lawrence. Worst case, suburban sprawl sprawl into the Greenbelt. St. Clair already has a streetcar, so I probably won't live to see it get a spur line branched off Line 1 St. Clair West. Lawrence's corridor cuts through Bridle Path, so that's a political non-starter. IMHO Midtown Toronto is destined for more congestion. Ironically, if Line 5 is slower than the bus, that might actually save it from eventually hitting overcapacity more than anything else.