Who told you that it will be 40Mpixels and not 45? "will possibly" is a way to stay a fact? TROLL ALERT!
ALL mirrorless cameras take fewer shots per battery charge. You compare apples with oranges! TROLL ALERT!
Panasonic has 24mp and you complain against the possibility that canon has 40! TROLL ALERT!
Panasonic takes Approx. 400 Shots so less then 5DmKiv (Which is a very good number but still it is a mirrorless camera so the difference) TROLL ALERT!
And last: Possibly, possibly, possibly: TROLL ALERT!
& Who confirmed you that it is 45 Mpx & not 40 or even 31 Mpx!!
clearly Canon has not said anything on Mpx in the announcement & no mention of codecs, ISO improvements , DR improvements or bit depth for video either.
What kind of Development Announcement was that ?? 8K ?? 
It looks like Canon marketing may have been forced (or even preempted) to announce
this 8K wonder of R5 camera as they may have got news that SONY might announce something big with A7S3 or A74.
& why are you assuming 8K will be 1:1 readout on R5 ? to have at least 40 mpx as your assumed resolution
& How can canon let R5 spit out 20 frames( at say 45 mpx ) when the 1DX3 can do the same at 20 mpx ??
clearly there is a catch here.
Canon has a history of crippling lower end cameras so that they don't hurt the sales of Higher end one's.
& battery life will make a hell of a difference to the 5D4 pro's if canon wants to switch them to R5. It is major.
For 5D4 PRO's to switch to R5 it has to be significantly better than 5D4 in every aspect.Period.
RF glass is expensive as hell so business wise one has to justify switching from EF to RF is well worth it.
& Don't just be a blind canon fanboy; look at the competition...look Fuji is coming to beat you & so is Panasonic. The majority of high Mpx 5Ds crowd i know has already switched to Fuji GFX50 & the video crowd have already switched to S1H.
Canon needs to deliver a very heavy punch with R5 both in photo & video to win back those who have left or are about to leave...but that looks like a tall task.