Football exists outside Europe, many leagues have a winter break anyway.
Yes but we don't so would affect scheduling. Also affects champions league. Teams could play in the knock out round with reserve teams because all main players are at World Cup. This delays everything and put its out of sync.
Amd the holidays things, if you play continuous football for pretty much w years at the highest level, with only a week or two off, you will suffer for it towards end of year two. Any human is like that in any job. Look at cesc, he played World Cup on year, so pretty much had two years continuous football amd suffered towards the end with fitness, causing had, to the team, multiply that across the league, everyone suffers, therefore tea,s and quality of football suffer all becaus FIFA took bribes to give it to Qatar
European seasons will change to the summer to accommodate the World Cup.