I think this is a good occasion to talk about what makes SAP a successful software. Does S/4 have the magic ingredient that made R/3 so successful? So why was R/3 a success?
When I started working with R/3 I was very impressed with the development environment, the tools in SAPGUI to develop the code running in the server, and how easy it was to start debugging a running program. At that time I thought SAP was great because it was based on this flexible development platform.
But of course some time later I realized it was not the platform. The ABAP language is a pain and lacks in many areas, for example it is quite bad for numerical algorithms. Concurrency is not very efficient, the web layer is slow and the many web frameworks are obsolete even before having some real adoption. Forget it, it was not the platform.
What is really cool in SAP is the applications, having so many applications, for so many areas, industries and processes. But usability is bad, performance also not so good, and there are so many custom applications in SAP projects that something must be wrong with what comes out-of-the-box.
The applications helped a lot, but something else was very important in R/3, the expensive price tag. I'm not joking here, a very expensive price is a powerful feature. When a software costs 1k either it works or it will be scrapped, no client will pay 10k or more in consulting time to adjust and integrate the software. But if the software costs 1000k then 100k in consulting is very reasonable. And if out-of-the-box things don't fit well, after 100k of consulting a lot can be done to make the client happy.
Will S/4 will have the R/3 magic? Yes I think we can trust it will be quite expensive ;-)