The only good replacement for the CVPI is the PPV Tahoe.
Having had a CVPI and been in an Ford Explorer based Police Interceptor Utility for fire and rescue, I can tell you that the police interceptor utility is far better and more versatile than the CVPI.
The FPIU is a very good patrol vehicle and offers utility over and above what the CVPI offered, but my first two tried to kill me with exhaust gasses and were never as comfortable for spending 8+ hours a day in as the CVPI was/is. The non-turbo V6 offerings are meh (if I'm going to go slow at least give me the SOUND of a V8) and the turbo engine is prone to trouble. The 2020 is an improvement but will never be what the CVPI was, and that's OK as long as you're not expecting it to be. It's not a bad vehicle at all, overall.
The Tahoe is roomier, faster and despite it's size makes for a decent around town patrol vehicle, only making you notice it's how bulky it is every so often. The Tahoe is a good 10K more expensive than any of the other alternatives, but reliability is excellent. It's good at what it does but it's not practical. Great for highway patrol type stuff (and bigger state budgets).
The Charger is a rocketship but reliability is horrible. Not as comfortable as the CVPI or Tahoe. Roomier than the Explorer but harder to get in and out of. Visibility lacks. Decent car (especially the AWD version) but only does a few things well at the expense of others, whereas the CVPI did most everything well.
The Durango is actually a pretty good option lately, especially since 2020 (or 2021) will see a pursuit version with steel wheels and a HEMI (reliability problems?). It's larger and more comfortable than the FPIU yet not as cumbersome as a Tahoe so it works well in daily patrol settings. Price is lower than the Tahoe and on par with other options. Overall reliability is better than the Charger because the Durango platform (Mercedes based since 2011) is VERY well sorted out and tough. I think you may see the Durango really catch on soon.
Each of the current cop offerings has it's shortcomings and it's advantages. I would not say any of them is the "only" good replacement - none of them do what it did. I think most on the job the vehicle is intended for (not fire/rescue) will tell you that the CVPI was the jack of all trades and will never be suitably replaced.
