Well, alot has been said here already...
I'm 100% f2p, but playing since the end of the last summer or so, so right now i have 1,5M + base SED and 500+ Stamina. Which lets me always rank above 500, and get all the event limited cards (except those from Event gacha, since, as an f2p, i am very limited in e-gacha tickets). The only stuff i miss are some Rgacha limited cards from "R-Gacha mini-events", a couple of 51k reward RSs from pervious Gambits (though, one of them i got from Revival Gacha later) and cards from teh first Events (since i simply wasn't playing back then).
I have alot of time to play, so i spend like 10 hours a day in the game, keeping my Stamina not full, and i try to use my E-Gacha tickets only when i feel i can't get all the rewards without it (Gambit or Shards events, for example). By using one or two, saved during EG, i manage to get enough Shards to trade for all 3 new limited shard cards every time (and even if not - they still allow you to save your shard leftovers and get the girls you've missed during next Shards event) and for the last 2 Gambits i even managed to get 51k reward SRs again, by using all E-Gacha tickets that i saved so far.
In EG my friends with 2M+ SED and Slayers help me deal with teh SEGs i find and the ones they find and share with me, so by just poking all the bosses i see wit h1 focus attack i get tons of SR Wild Cards, and otehr loot, and manage to end up in high ranks and get all the rewards.
So yeah, it is possible to get most of the rewards without cashing and, i hope, one day it will be possible to get the cards i missed from teh Revival Gacha. Though, it is still unclear how to get stuff like old Gambit story chapters and Elite Guard movies from events you haven't played or completed successfully.
So yeah, you can do quite good as 100% f2p (but you have to wait and grind ALOT first) but you'll probably miss some content anyway. For me - it's a big tragedy, and you have to decide, if it is fine for you. If your goal is not a 100% full collection of cards, movies, etc. - i guesss you're fine. Just wait and levelup. Then you only have to decide if it's fun for you to play PPS or is it tiresome. But yeah, if you'll stop playiong - you're going down. You'll miss content, miss Slayer cards, and eventually, all your gacha tickets will expire and you'll lose them. So, if you'll do a very big break - i'd rather not come back at all, as i did with LoV.