No, but for different reasons.
You are wanting an inline function, when executed, that looks in the current workspace for the value of mycondition, and returns a value selected by it.
That would require that the inline function had no parameters.
However, the internal implementation of inline functions always requires that they accept at least one parameter. The function is not required to do anything with the parameter, but it needs to be passed.
There is no inline function equivalent to
f = @() [falsestatement(repmat(~mycondition,size(falsestatement))), truestatement(repmat(mycondition,size(truestatement)))];
because you cannot implement that () empty parameter list for inline()
If you were willing to have the condition be passed in to the inline function instead of expecting it to be read out from the workspace, then that would be do-able -- provided that the values of falsestatement and truestatement and mycondition could be copied into the inline function instead of being referenced dynamically. But pulling out workspace values dynamically is hard for inline functions.
Why do you want to use inline() ? inline() has been recommended against for a long time.