In Hamlet, "Polonius shows what Laertes would have become, Laertes what Polonius once was." Is this true or not?
I think one place where you see Polonius in Laertes is in Laertes being upset over the appearances of things or in the family reputation. He specifically mentions the hasty and probably low key funeral that was held for Polonius. He calls it an "obscure funeral / No trophy, sword, not hatchment o'er his bones, / No noble rite nor formal ostentation, -- / Cry to be heard." Just as Polonius acted to improve and impress his reputation around those around him, so it seems Laertes wanted a public display of Polonius's importance to the state of Denmark at his funeral. We see this again at the Ophelia's funeral when he asks the priest for more to be done, but the priest claims that more has been done (a Christian funeral at all) than should have been done. This doesn't satisfy Laertes, and he gets overly emotional, condemning the priest and actually opening the coffin to see Ophelia one last time. He wants more for her and is devastated that she is getting only the most basic of services and reverence at her death.
I'm not so sure. Laertes seems to have way more aggression and energy than Polonius. I suppose that part of this could simply be age, but I think part of it is personality. I have a hard time seeing Laertes growing up from his hotheaded and impetuous self and becoming a fussy old guy giving out advice like all the stuff Polonius says to Laertes before he heads off to France.