It's not that your idea is bad, but it's completely unrealistic. The ticket shop already exists, but we don't have a pity system yet and even in Dokkan, another Bandai game, there isn't one similar to this. Even if it's usable once, I doubt they would ever give us a chance to get the newest units with a 100% certitude the moment they drop. Later on? Maybe, with the ticket shop if they can update it and make it 500 for LL(maybe 600 knowing them) and less for regular SPs with them rotating based on the current step-up banner, then I could consider it more realistic. But as I've said, I simply don't see them giving us the new unit for free even if you summon X times on it.

Unless the tickets would only give 100 Z Power once to get the unit itself, but even then, like I said, I doubt they would do something this generous.