In terms of Meta, what do you think it would happen? Which champions would become God Tier and which ones would instantly become garbage? Would Ghost replace it or would people go for more aggressive choices?
Mobile champions -> god tier Immobile champions -> trash tier
Gank Junglers would take over
Annie becomes trash.
Mobile champs obviously
actually the game would be more balanced and funny to play (downvote tsunami in coming)
sure if they just remove flash immobile champions will suffer,but it would make easier balance them since actually they have to consider in their power budget that they can have some mobility sometimes,if a champion supposed to be telegraphed and slow can suddenly flash in your face is not fair for the ones that have mobility in their kit (since champions with mobility usually give up something for being mobile)
i mean,atm having a champion supposed to be immobile (so balanced around being immobile) dodging your main skillshoot with flash feels so bad
so removing flash would make mobility more relevant but more balancable as well
let's make some example
i'm playing cassiopeia,ahri tries to engage me and i dodge her E with my flash,i do my combo and she dies,i don't think it's fair since cassio is supposed to be immobile so in this situation she should be pusnished but it becomes a reward because of this summoner spell
malzahar got nerfed many times for his ultimate,one of the reasons is because it feels so bad when he can flash + R and pick you,and they can't give him tools for engaging his enemy because it would make him too strong,some of his power budget is exatly this combo (no wonder he's used with spellbook),but i think if he couldn't make this combo (that actually have 0 counterplay) it would be easier balance him,they could add some movement speed buff or some slow so he can try to engage with his ult without becoming obnoxious
so many champions are balanced around flash (some got reworked or nerfed only because this summoner spell exist,like annie and cassiopeia),removing it would mean solving some champion problems,making easier balance the jungle role,and damn i hate having only 1 slot for summoner spells because if you don't pick flash you are trolling
######sorry for the wall of text,but i would really love this summoner spell getting removed,i consider it one of the most toxic spell of this game
Jarvan becomes p/b
Annie bot would stop playing League altogether.
At the very least, you will see a wider variety of alternate summoner spells. Even if every role continues to take their second summoner (heal on adc, exhaust on support, etc) you could see a lot of counter-summoners picked - see a leona in bot lane? Better take cleanse as the adc. I think a lot of under-appreciated summoners will become more viable, but I also think a lot of champs will simply replace flash with ghost.
People would use HTML5 player instead
Goodbye 
Removing flash would likely be the biggest buff immobile champs could get. Champs with mobility benefit from flash far more than those without.
But all of these plays can be done flash-less too. I understand what you mean, but it's not like they're losing Flash-Tibbers or Illaoi Flash-Ult, they'd survive the purging.
Also in a world without flash, Toplane becomes the new Camille Bar. Forget season 5's Renekton Bar or Season 6's Gnar-Bar. If you don't jump the Camille Bar, you get cut down, literally.
Riot would have a reason to rework half the champions to actual self-centered balance.
All the females would suddenly lose the urge to remove their tops every 5 minutes...
Well, I never take flash so my life would be basically the same...
Honestly the game has used flash as a balancing crutch for so long hardly anyone could function without it. The best champs would end up being the ones with the most mobility and everyone that doesn't have any just becomes trash tier.
Anyone saying immobile champions become unviable is an idiot considering those champions go through the majority of the game having no mobility.
It's a 5 minute cooldown that can be up for an extended period of time as you try to save it for crucial moments.
The champions that are most hurt by losing flash are those like Gragas or Lee Sin who lose a piece of their combo.
Obviously Mobile champions would dominate the rift & so would Junglers that are great at ganking pre-level 6.
I would obviously use 
, that's what I used before I actually started using my keyboard to play the game back in Season 4.
It'd require a huge balance overhaul even larger than the rune rework since this would go beyond mere stats.
It would lead to a heavy nerf of the mobility creep that happened, particularly for champions that could clear walls/teleport.
I personally feel that the game would be a little more interesting, because it would mean that the summoner you now depend on most would be heal, and your supplementary would be incredibly important to how you play the game, rather than just the flash-heal meta we've had for ages now
Jungle will be the most wanted role
People would have to use an item slot for a mini flash on Protobelt.
Kindred becomes ultra-god tier, along with Zac and Ezreal. And probably Leona as well, since no one would ever get away from her.
Immobile champs would feel horrible to play...
