If there (be) a major flu epidemic, many people (die).
If there is a major flu epidemic, many people will die.
Everybody (be) online 24 hours a day if the number of Wi-Fi hotspots (increase).
Everybody will be online 24 hours a day if the number of Wi-Fi hotspots increases.
If the Earth (become) too crowded, humans (live) on Mars.
If the Earth becomes too crowded, humans will live on Mars.
If young people (put) too much personal information on social media sites, they (regret) it when they are older.
If young people put too much personal information on social media sites, they will regret it when they are older.
Governments (ban) cars if global warming (get) worse.
Governments will ban cars if global warming gets worse.
Ordinary tourists (go) to space, if the tickets (be) not very expensive.
Ordinary tourists will go to space, if the tickets are not very expensive.