dynamic path in workflow?

[tooptoop4]

is it possible to have a workflow that has a dynamic middle step (with dynamic image)?

ie
if output of stepA is x then
step A>step B (running image x) >step C

but if output of stepA is y then
step A>step B (running image y)>step C

but if output of stepA is 'no-op' then just
step A>step C

the images x/y should not be hardcoded anywhere as i want to arbitrarily run any image name returned by the output of stepA

would also be good to have resources.limits for next step set based on output of earlier step

cc @alexec