1)
When will Hashem make Egypt desolate?
1.
Malbim: This will be in its final Churban.
2)
What is the meaning of "[u'Nshamah] Eretz mi'Melo'ah"?
1.
Rashi: [Will be desolate] a land that is now full of all good.
2.
Radak: The land will be desolate of all its fullness. Even though the Ta'am (note) on u'Nshamah is a stop (not read with the following word), u'Nshamah is connected to the coming word (Eretz). U'Nshamah is female Nif'al conjugation, from the root Shamam.