Other presumed subfamilies of Altaic are undoubtedly out of the Indo-European range.
Sorry, but that does not make any sense. The Turkic languages, or the Altaic languages (by whatever definition) are demonstrably not (closely) related with the Indo-European languages, and certainly, the Turkic languages are not just another branch of Indo-European. The Turkic languages have a completely different grammatical structure, being agglutinative, while the Indo-European languages are fusional. This is why in the past, the "Ural-Altaic" hypothesis was popular, as the Uralic languages are also generally agglutinative.
Altaic in this case is a distorted code name for Turkic. This is a very important distinction criteria.
I'm sceptical on the inclusion of the inclusion of Japanese and Korean in Uralic (especially the former), but in my opinion, the case can be made for a "narrow" language family composed of the Turkic languages, Mongolian and Tungusic (e.g. Manchu). Even if you discard the Altaic concept completely, and consider the similarities of the Turkic languages with Mongolian and Tungusic to be the result of some kind of sprachbund, its clear that the Turkic languages have a close relationship with these, and not with Indo-European. You also have common religious concepts. For example, the modern Turkish word for 'god' (in the sense of the monotheistic God of the Abrahamic religions) is "tanrı", which is a cognate with the Mongolian word for "sky" (tenger), which is also, in the old Altaic religion (Tengriism), the eponymous sky god. You're also aware that one Turkic language, Yakutian (also called Sakha) is actually spoken in Far-Eastern Siberia.
So, no, Altaic is decisively not a "code word" for Turkic. Unless you consider the Mongols and Manchus to be Turks... :wink: