you are correct, the search button on the phone will not pop up google search. For me...Im glad it doesnt...because sometimes when I hold my phone in sideways orientation, my finger accidentally touches the search button and it pops up over my text or whatever Im doing.
but..yes...it will not work any more if you update. You could always rename it .bak at the end...reboot...try to install google search, then rename the .bak back to .apk...and see if that works for you. You could have both functions there.