What would happen to a plant if its cell membranes became as elastic as the cell membrane?

1) The cell wall gives the cells stiffness and a certain shape, become soft.

2) If plant cells lost their cell membrane, the plants would become shapeless, because the framework would disappear. Remember, many animals have rigid structures that help them maintain their body shape (for example, a chitinous exoskeleton in arthropods; a pronounced whole in annelids, which performs a supporting function; bones in vertebrates) or are able to support it with muscles.