= Solution
The likely effect in a single-cycle or unchanged pipeline-stage implementation is a \b[longer <combinational critical path> and hence a lower maximum <processor clock frequency>]. Previously the <barrel shifter> and <ALU> could work in parallel before result selection; the modified path can require both shift and addition before address or result use.
Ignoring common <processor register> and wiring delays, the relevant <combinational logic> contribution changes roughly from $\max(t_{\mathrm{ALU}},t_{\mathrm{shift}})+t_{\mathrm{mux}}$ to $t_{\mathrm{shift}}+t_{\mathrm{ALU}}$, with any additional input selection included as needed. The <processor clock period> must also cover <processor register> timing and the rest of the instruction path, potentially including memory access. Removing a <multiplexer> offsets some delay, so a numerical frequency change cannot be inferred without component timings. Pipelining, a faster implementation or another pre-existing bottleneck can alter the outcome; the changed serial dependence is the reason for the likely reduction.
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