This has never been a problem in the 2000s - either utilise a TV (or box) with Picture-In-Picture, or use a mobile or tablet at the same time as a TV. I've been doing this for all the major International football tournaments since I think 2010.
Before the 2000s, multiple TVs, or even watching it on one TV (with the sound down, cos big mouth commentators will ruin the scores of the other game) while recording the other on VCR (and watching it back immediately after the first game).
Agreed. 48 is too much, and means you have to have weird hacky ways of guaranteeing the next round of knockouts is 16 or 32 (in this case, 3 group teams). It's almost as bad as UEFA increasing the European Championships as well, which definitely shouldn't happen considering there's only 50+ nations affiliated to UEFA. It's now so big that it can't be hosted by just one nation any more (although I'm sure the bigger nations such as England, France, Germany, even the US could but it'd be insanely expensive).