That's pretty much my opinion ...
The design of the CP pump is fundamentally flawed and there is no proper solution aside from full redesign, which they don't want to do, because admitting failure at this point and replacing millions of pumps in the field (remember, VW Golf/Jetta are not the only ones using this pump and are not the only ones having trouble) would be a multi-billion-dollar exercise.
The realistic hope is that they just continue to replace them as they fail, and in the longer term, that GM is only the first of many manufacturers to say "no" to the CP4.
This is the best analysis of the Bosch CP4.x saga I've seen on this site. If you look at the industry in general at the time frame that the CP4.x pump was designed, it adds some insight as to what may have happened.
In late 2007/2008, around the time the CP4.x was being designed/tested and targeted toward a lower price point than that of the previous CP3 pumps, the automotive industry was in financial chaos. The economic crisis of 2008 had ripple effects on the auto industry, with unsold new cars sitting in storage fields, ships in the Pacific and elsewhere by the millions, because automobile sales tanked, while manufacturing was still cranking them out at a pre-crash rate. GM and Chrysler were headed into bankruptcy and their vendors were suffering badly. Many went out of business.
The destruction of the housing market had ripple effects - people were no longer using their bubble effect home equity to finance new car down payments. Banks were failing dramatically. Credit was severely impacted.
I looked at Bosch's financials in 08/09 and IIRC, they lost almost 2 billion euros. It was a hard time for everything automotive. Cost cutting was no doubt top priority. At the same time that the new car market was imploding, cost pressure from the likes of Hyundai and others put even more pricing pressure on VW, GM, Ford, Chrysler, Toyota, Nissan and Honda.
When taking all of this into account, it's not a surprise that an attempt to drastically cut the cost of the HPFP in diesel vehicles occurred, even as EPA regulations required the ever increasing high pressure and costs associated with them. Something had to give.
In the case of the CP4.1 used in the VW and other vehicles, it was rated design life - 94K miles (150,000 Km) and warranty - 3/36 instead of 4/50. That's what we know from VW documents, I don't know if we have the NHTSA design life from Ford, GM, Chrysler and others on their Bosch CP4.x hpfp'.s We know they're failing on those vehicles as well, while their earlier precedesor, the CP3 continues to run very well on the same US spec fuel.
That's why I think the Bosch line about contaminated fuel is a scapegoat, because they built a pump that can't handle the US fuel. Someone earlier posted something to the effect that emails from VW engineers revealed that their fuel sampling wasn't showing the degree of fuel contamination that Bosch was claiming. It appears to me that Bosch is stonewalling with everything they can come up with, to cover up a defective product. VW, likely has no choice but to go along with this, unless it gets so bad that like Ford, they end up in a lawsuit with one of their major suppliers.
I posted a pdf some time ago showing one of the reasons that solenoid injectors were upgraded by Bosch to compete with piezo injectors - it was a single reason and it was cost. Bosch already builds a reliable hpfp for US fuel, the CP3. GM is using its predecessor, the CP1H, so we know it can be done, but can it be done at the same lower cost as the CP4.x hpfp?
That's why I agree with GoFaster's assessment that the pump is fundamentally flawed, because in their quest to cut cost, Bosch went too far. Just looking at the size of the roller that sits between the piston and pump cam, comparing it's diameter and the camshaft diameter to derive a speed multipler ratio, it seems that it's going to run at least 2x times faster than crankshaft speed. That's pretty high speed compared to the CP3 design, which doesn't have a roller, just a 3 sided crankshaft that converts rotary motion into vertical motion. Softer material and higher speed have not proven very reliable in this pump. So using even 200 bar ( ~3000 psi) less pressure on that tiny roller and possibly a better grade of DLC coating may well be why the Passat CP4.1 HPFP is lasting longer. But with a design life of 94K miles, I don't think we can expect the same real world long life of the earlier CP3 pumps that the pickup truck world has been experiencing.
I also agree that at this point, any redesign of the pump is an admission of design flaw and the cost to issue a recall would be astronomical for Bosch and VW. IMO, and it's only an opinion, VW went for the odds on this one and they lost.
I've been wondering what the upside is for VW/Bosch to just replace the hpfps until the next gen engine comes out and I don't see it. If the pumps continue to fail on these cars as they approach 6 to 8 years old, the loss of resale value will hurt VW more than it will Bosch. It could well be the equivalent of Chrysler's transmission reputation of the 1990's, even though VW didn't make the CP4 pump. At some point, they may have no choice but to sue Bosch over this.
I too see GM's use of the CP1H as a possible out for VW, under the cover of lowering costs, (as they've already done with solenoid injectors on the Passat) - it set the precedent, showed that current emissions can be met with prior gen pumps without the poor reputation of the CP4 in multiple manufacturers vehicles. It's either that or they buy/license 2Microns pure flow design and start retrofitting them to every CP4 equipped vehicle they sell.
Only time will tell.