''Yes: there were SOME Nubian dynasties''

Not just some since even narmer according to egytologist Professor Bruce Willams says that was probally closer to nubian.
Also ta seti which is the offical egyptain name for nubia was alwayts apoart of egypt since even since pre dyanstic times.

12th dyansty in Ancient egypt was started by a nubian and it was considered the pinacle of civlization where much of the mathematic,scienitifc and litterture contributions come from.
According to Herodotus,who some called the father of lies it could have been senwroset I who colonized and founded athens,but mre archeological work needs toi be done in this reguards.

''There is a strong Semitic strain in the Egyptian language, especially notable in the Old Kingdom''

Well actually this is incorrect since Egyptain lexicon is probally more similar to languages like ormo and chadic than it is to semetic dialects. However what you neglect is overall even in caanite,there are egyptain influences. Many linguist know believe that the alphabet atrributed to the phonecians,could of been the product of egyptain influenced semetic mercenaries who lived in egypt.

Also accoreding to linguis Joseph H greenberg the semetic language itself could have originated in what is know ethiopia,and spread by African immigrantsd into the middle east,but more anthropological work needs to be done in this reguards.

The evidence is strong though for the semetic having an Africna origin.
The nearest relative to the Ancient egyptain language is coptic,which is still spoken in chruch services in much of egypt.

''Yes: the Black Negroid gene pool was a major CONTRIBUTOR to the complex demographic picture of Egypt in all periods, including the pre-dynastic, as I have been saying''

I am glad when can reach a standing ground,because this cannot be denied and it can still be seen in much of upper egypt amung the fellahin.
The fellahin by the way are largely indigenous,and have not really mixed much with arabs who came in small migrations and mostly lived in cities. recent y chromosome studies I have seen however confirm that modern day egyptains might be more mixed than people think.
Many people wrongly in the united states believe that coptics are the true desendants of egyptains,but this is inncorrect since most of the egyptain population was at one time coptic. Much of the modern egyptain arabic even though greatly inbfluenced by syrinic arabic is vastly different because of the coptic words it contains.

Many coptics in lower egypt including pope shenouda are syrian in origin,but many people who think all the coptics are light complected might be suprised to find that coptics around luxor,aswan,and other places are very dark brown and have kinky hair texture.