AHC and WI: The Do 31 enters serial production

In 1959 the Bundeswehr ordered Dornier to develop an VTOL transport jet for 36 soldiers. What they came up with had mostly better performance than the V-22 has today, especially a far greater speed, though it also was larger. By early 68 it had its first VTOL flight and all test pilots, including those evaluating it for NASA rated it favourably.
But when the contract ran out in 69, the Bundeswehr had lost interest and Dornier was not big enough to continue on its own when the NASA decided against supporting the program in 70. The main complaint was the compared to conventional planes reduced range and payload due to the drag of the (removable) VTOL pods.
So how can the program be saved and what could be its effects?

DO.31B

The technology part worked, I believe; but the operating cost was seen as prohibitive.

They were looking to upgrade the engines, as they came available. Would the availability of more powerful, less fuel consumptive engines made enough of a difference - to keep the program running?

Everyone got on the lift jet bandwagon, at least, for fighters, and everyone except Yakovlev got off because lift engines are mostly dead weight, expense, complexity, and maintenance. Adopting the Armstrong Whitworth concept of the still-born AW.681, using 4 Pegasus engines would result in an aircraft that is still expensive and complex, as well as expensive, but if VTOL is the goal, there is a price to pay. It all depends on having somebody with deep pockets and grim determination, like the USMC, to carry the program through. It wouldn't carry as much as a conventional STOL a/c, but Sikorsky always had the pat answer for people who criticized helicopter limitations. It would do what no conventional aircraft could do.

Dornier Do-31 with 4 Pegasus.

Perhaps have an alternate Vietnam battle result in the US demanding a similar aircraft (learning the lessons learnt in OTL during the Iranian Hostage Crisis).

As a result, the Do 31 attracts far more interest and gets picked up as a joint American/Bundeswehr project...