Euro 6 diesels vs ULEZ zones

[SlowV6]

Hi,
Does anyone have any inkling as to if/when euro 6 diesels may become impacted by ULEZ charging?

Or is it pure guesswork suffice to say "one day".

Am conscious of the risk of spending £13k to £20K on a 530d in either F11 or G31 flavours vs the "safer" bet of £20K+ on a 340i/540i. Thanks!

[ZX10R NIN]

The next change will be for euro4 petrols to have to pay.
Remember there is no euro7, so you'll be at least 10 years before Euro6 cars could be penalised.

[M28TTR]

I spent 20k on a G31 520d last June and have no worries about being penalised just yet, once I move it on in 5yrs time I will probably go 545e of the new shape or 540ix G31