Being a victim (some say: customer) of the Deutsche Bahn (with bahn.comfort black status): I sincerely believe they can not. After 40 years of ignoring maintenance, never setting up the East-German rail system for success, I honestly believe the system is broken beyond repair. What is indicative of that is that they believe they can make the Deutschlandtakt work by (no typo!) 2070.
There was a time when there was no railway and a time were we had a good railway. That is not out-of-reach, but it is mostly a political problem, not a technical one.
Unfortunately, they realistically cannot. Basically every major infrastructure project gets loads of local opposition which would require substantial political will. However, the currently elected government is the government that let the rail infrastructure get that bad in the first place
AFAIK to fix reliability no new major infrastructure projects would be required (at least for most of the reliability offenses). They would just need to maintain/modernize existing infrastructure and rolling stock, so all things that aren't really opposable.
To achieve the Deutschlandtakt as noted in the article, yes new infrastructure projects are required, but I think most people would be happy with all the existing service running as well as it has ~15-20 years ago.
We get what we have, and that's it.