I'm a little late to the discussion, but since I recently took a look at our future on defense I thought I'd share my list of players born in 94 or later that already are or will/could be playing on the national team in the future:
1994: Dominik Tiffels
1995: Jonas Müller, Fabio Wagner, Tim Bender, Janik Möser
1996: John Rogl, Kai Wissmann, David Trinkberger (NCAA)
1997: Lukas Kälble (NCAA), Simon Schütz, Tobias Fohrler (if he is eligible and wants to play for Germany), Maximilian Gläßl
1998: Maximilian Adam, Johannes Huß, Pascal Grosse
1999: Leon Gawanke, Colin Ugbekile, Tom-Eric Bappert, Nicolas Appendino
2000: Alexander Dersch, Leon Hüttl, Yegor Alanov (if he is eligible and wants to play for Germany), Eric Mik, Daniel Wirt, Philipp Mass, Tobias Möller
2001: Moritz Seider, Tommy Pasanen, Simon Gnyp, Mario Zimmermann, Philipp Preto
2002: Maximilian Glötzl, Maksymilian Szuber, Maximilian Menner, Fabrizio Pilu, Arkadiusz Dziambor
Obviously not many of them will totally pan out, but at this point I feel they are the most likely candidates to make any impact on our blueline at some point.
I think in the short term Lukas Kälble could have the biggest impact of those that are not already playing on the national team.
I believe Steven Raabe (2001) has also played some defense. Should he switch permanently he could also be a candidate.
Indeed, the two bolded names were kids I wanted to include in my post above, but their names slipped my mind while composing it. I have it on good authority that plenty of NHL scouts know who Kalble is and are watching his NCAA development. His sophomore season at Lake Superior was really good (23 pts, +17) and he has great pro size.
That same authority also says that Michaelis (and depending on his season, Tuomie) are guys the teams hope will be part of the college UFA frenzy next spring, but they're forwards of course. As is Napravnik, who has plenty of time to develop his game in college.
Pasanen is a very fascinating prospect and Germany kind of needs to hope that he'll see himself as a German in the future. His initial USHL season was nothing to write home about, but his size is outstanding and he may just need time to develop. I'm assuming that he too is looking to go the college route.
As a sidenote, Zimmermann is the smallest spit in the bucket I think I've ever seen playing "pro" hockey in Germany. Still, his stats for the promoted Landshut Cannibals team were pretty fantastic for a kid who just turned 18 a month ago and all indications are that they are planning with him in the DEL2 as well, which is awesome.
Many of the names you've headlined such as Ugbekile, Bappert, Moser, Huttl, etc. were names I choose not to mention above, because although each may sniff some time in the national team along the way, I'm more concerned about which blueliners are going to take this team to the next level. Even if we choose to see Seider as the next Uwe Krupp (and heck, he might be better), how many Erhoffs and Seidenbergs will he have joining him on the blueline while he's in his prime? Will Germany one day be at the WC, Olympics, World Cup of Hockey, whatever with a blueline that is 8-men deep in guys who are in the NHL? Or perhaps also a few in the KHL, NLA or SHL?
I can't comment too much on the 2002s, but I can make a general statement that I do think there's good reason to believe that Germany will have two entire NHL lines by 2025. They may even have three forward lines and sure, several of those guys may not have roles bigger than those we're seeing for Rieder and Kuhnhackl, but I think the PowerPlay26 program has already began taking major effect (and believe me, the program is not perfect, but that's a topic for another thread). I also think that by that time, there'll be another handful in the AHL and perhaps in a few of Europe's top leagues as well, KHL included.
Things are definitely looking upwards! But the country has had a terrible time of producing world-class Dmen.
PS) Hard to tell if Alanov will ever be seen as German internationally. What we can definitely say is that his past two seems for Red Bull Akademie and Växjö have been VERY good. I'm hoping he'll be part of the picture for Germany moving forward. Won't really know until he one day suits up for a Team Germany.