The Z80 was still being used in embedded designs in the 90s. One company I worked at was still supporting Z80 systems and s/w at least until around '94. Possibly later, as I didn't work on those.
In the UK, I never saw a 6809 used in embedded designs (late 80s - mid 90s), I did see plenty of Z80s and 8051 derivatives.
However by that period (late 80s on) a lot of those embedded designs were using NEC V20/V30, as they made for easier systems to program than plain 8bit systems; plus the price range of the systems I had experience with allowed it.