TL;DR: These rules were written to ensure that none of the companies implementing game streaming will follow them. It's effectively the same as banning them, and the expertise required and cost of starting a new cloud gaming service is so high that there are few companies capable of it, so we probably won't see one started to fill this iOS niche (although it's not impossible).

Service-by-service:

Project xCloud (beta name), it's Microsoft's cloud gaming service attached to Xbox Game Pass Ultimate. The 30% cut is probably not viable to give up. They just announced that EA Play will be added to the service, further reducing their margins. Since they would be required to offer the same price as elsewhere, I don't expect them to invest in iOS.

PlayStation Now. Not currently available on mobile devices, but Sony committed code to Android 10 to make the DualShock 4 (PS4 controller) work properly over Bluetooth, so who knows? That code is also used with their PS4 Remote Play app which is available for both iOS and Android. Sony has not hesitated to kill off loss leaders (I'm thinking of PS Vue in particular) and the service isn't all that popular as it is, even though it beat all the other competitors to market by years, so I don't see them investing further into this service unless it picks up a lot more customers. (They may see this as an opportunity though, so it's a possibility.)

Nvidia GeForce Now. This is a complete non-starter as games are not sold at all by Nvidia, their subscription is effectively selling server time. Players can play a subset of games they already own on other digital storefronts. Since games cannot be purchased in any way, neither by subscription nor individually, the "app" downloaded from the App Store would have to be purchased elsewhere which I believe breaks another App Store rule.

Google Stadia. Saved this one for last as it's the most likely of the bunch to give in and follow Apple's rules, although I'd still consider it a toss-up. Unlike all of the other services mentioned here, Stadia does sell games individually in addition to their subscription, which more closely meets the intent of Apple's setup (that each game is "downloaded" separately). Google has the engineering talent to roll this out quickly, if it's possible on a business level, and they are evidently willing to burn the capital necessary to acquire more consumers due to their other actions in this space. So Stadia on iOS is a distinct possibility, even if Apple's rules make it difficult and potentially unprofitable.

In addition to the problems above - for each service, each game would have to be looked at by the streaming provider and potentially altered by the game's original developers on a game-by-game basis to implement Apple's IAP requirement; given in particular the 30% IAP cut, AAA publishers' reliance on microtransaction revenue, and Apple's requirement to not charge a higher price than elsewhere, I don't expect them to bother, but you never know. This also means that the streaming provider might have to use a different version of the game depending on whether the user is streaming from an iOS or non-iOS device, but that's also an unknown regarding the internal implementation of their in-game purchase API. It's the 30% cut that's more important here though.