The city and the development are planning to build an extension of Glassworks Drive (sort of like a switchback) to meet Eglinton. You could even see it in some of the renderings.
Yes the completion of Glassworks Drive has been planned all along and has been depicted in renderings and discussed at Crosstown meetings for at least 10-12 years. Glassworks Drive (in its entirety) already shows up on the City of Toronto on-line maps.
And the intersection between the old Celestica interchange (which will become the western end of Wynford Drive) and Don Mills Road has been depicted in the Crosstown condo development renderings.
But none of these intersections will be have to be used for u-turns because there is ZERO CHANCE that the Leslie and Eglinton intersection will be closed to any turns of automobiles. I don't think some people here realize the volume of traffic that goes through there; especially at rush hour but throughout the day. That's one of the reasons that people at the Crosstown meetings pushed to ensure that the TWO eastbound Eglinton to northbound Leslie left turn lanes would remain after the Crosstown LRT was completed.
Also, to clarify a myth about the stop at Leslie (Sunnybrook Park stop): It wasn't Leaside residents who pushed to include this stop. (They would never walk all the way down the hill from Brentcliffe to use such a stop anyway). It was a few residents from the condos on Leslie (north of Toyota on the Park) that pushed to retain the stop. Ironically they would probably not walk half a kilometre down Leslie to use it anyway (especially in winter) when the Leslie 51 bus stops at their door and would take them directly to Laird station where they could could wait for the LRT underground (warm and dry). The media got hold of the story and pushed it like Leaside residents pushed for the Leslie stop but that was totally false and wouldn't make any sense if one thought about it at all.
In fact some Leaside residents argued early on (2010-2012) for a south side alignment of the Crosstown through Leslie. This would have made both drivers and transit users happier. The Crosstown could be totally grade separated and ATC all the way to Don Mills and the Leslie-Eglinton intersection would remain as was for cars. They were told in no uncertain terms that this was impossible engineering-wise. Why? Because it was physically impossible to build a launch shaft and portal on the hill east of Brentcliffe. This is the reason Metrolinx used to push for underground all the way to Don Mills and build the TBM launch shaft at the SW corner of Don Mills and Eglinton. When the YIMBY's from the 3 condos on Leslie got upset about the loss of their stop (it would be too expensive to be built underground for the small ridership), Metrolinx after (arguing for over a year) caved in and went back to to the original EA which they had said couldn't be done.
When Leasiders argued that if the launch shaft and portal could indeed be built east of Brentcliffe (where it has in fact been built), then why not do the south-side alignment, they were told "Too late" It was good idea but now we can't risk opening up the EA- let's just start building and that's how we ended up with the clusterfuck at Leslie we have now.
Phew! (this has all been rehashed many times above in this thread going back 5-10 years for those that are interested in looking it up).
I personally believe that one other reason they refused a south-side alignment at Leslie is that they were holding open the possibility of a Leslie Street extension southward which has been talked about on and off for 50 years.
Anyway, with the present virus crisis I don't imagine the Ontario Line will be built now for at least 20 years so an interchange at Don Mills is not an immediate issue. As for Line 5 Crosstown trains, the headway east of Laird and west of Laird is so different that the service at Leslie will probably be infrequent enough to not be an issue with the intersection. The storage track underneath Eglinton between Laird and Brentcliffe is being built so that every second eastbound train can short turn at Laird. This will ensure that capacity up to and including Leaside is sufficient and will also have every second westbound train at Laird arrive empty.
Metrolinx could have avoided a lot of this mess but they weaseled around with half-truths and outright deceptions and the sham public meetings.
True foresight would have envisioned an Ontario line to Eglinton and they could have planned and allowed for a very efficient Lionel Groulx type interchange at Don Mills and Eglinton. While this would be expensive it would have been doable 5-10 years ago before the area got all built-up. Now it would be insanely expensive if not next to technically impossible, although we know that's never actually the case.
Oh well. We'll see what the future holds.