Well not be exactly like those boots. And no, if balanced correctly, no one would choose boots just for the Flash active, especially if it had a 300 second cool down. The reason Flash as a Summoner Spell is used so much is ALL THE SUMMONER SPELLS HAVE A LONG COOL DOWN! If flash with around the same cool down were put on boots, majority of the time they would just be normal boots. They could have stats for example:
Yordle Stompers
UNIQUE PASSIVE- Enhanced Movement: +25 Movement Speed
Active- Flash: Flashes your champion 400 units in the target direction. (200 second cool down)
This would make these boots very situational, but very beneficial to those who benefit from them. For example, a Fiddlesticks or ADC with no escape like Draven or Kog'Maw would love these boots, but someone like Lee Sin, Kha'Zix, Zed, or even Renekton would probably want different boots since they would only benefit from these boots every 200 seconds (3 minutes) and would want boots to more fit what they want, such as CDR Boots or Mercury Treads.