Westbound into Kennedy ridership is projected to be around 5,250 pphpd. The westbound peak ridership of the Crosstown LRT is westbound into Yonge Station at 5,400 PPHPD. Both ridership projections are essentially equal.
The only place on the LRT network that will have significantly higher peak ridership is eastbound into Eglinton West Station, with its ridership expected to be around 7,000 pphpd.
The impact of Crosstown West on the ridership of the central Crosstown hasn't yet been evaluated. But let's say 3,000 of the 5,250 Crosstown West westbound peak hour trips continue to Yonge Street. In that case, the peak ridership of Crosstown West would be 5,250 westbound into Kennedy and the peak hour of the central Crosstown will be 8,400 pphpd westbound into Yonge Street. Those ridership aren't equal, but it's not such a great imbalance that I believe it would cause issues.
It's also worth noting that City Planning wants the Relief Line northern extension under construction within the next 15 years. It is yet to be seen how this will impact the Crosstown. My hunch is that, because the Scarborough to Downtown trip is faster on the Crosstown + Relief Line than it is on the Crosstown + Yonge line, we'd have significantly greater westbound ridership east of Don Mills Station than west of it.