when the biturbo engine in my Kodiaq RS ****s itself (a near inevitability, as i intend to keep it for as long as possible), and a repair proves uneconomical, will it be possible to find a new replacement engine, bearing in mind the 176 TDI will no longer be an option for new cars ? 

The same engine is used in their vans. I’m sure there will plenty of reconditioned engines sitting around should you need one. 

A New Base Engine from the VW Group can arrive from a 'Refurbishing plant' where the block is reused and a  rebuild  done.

The engine arrives in a crate and is 'new' but just the block was 'reused'.

Euro 5 1.4 TSI's and others from vehicles pre 2014 are available now like this. 

 

Surely a cared for 2.0 bi-turbo is good for 20 years and more which likely is beyond when they are allowed to rattle about even in New Zealand

On 31/08/2020 at 17:33, chrisluciofg said:

...and a repair proves uneconomical.

 

You've answered your own question. If a repair is uneconomical then a new engine is unlikely to be much more economical.

 

Throw the whole car away and buy a a new one.