You're technically correct, but in my entire 65 years I've never heard anyone say "I can take whomever is next" in any situation. So, it's probably a case where overwhelming common usage has turned the expression, grammatically wrong as it is, into a colloquial expression taken "as is." For the same reason, we're probably going to learn to live with "I can take who's next."
Most English grammarians seem to favor 'whoever' in this case. Generally, it's defined by its role in the noun clause, which would be the subjective case here.
hehe, I was just looking at that one myself :) I've just read a dozen pages from various grammarians online on this. There is simply no strong agreement on the matter. Those arguing from the British perspective seem to distinguish them by degree of formality (written vs spoken) rather than by meaning, whereas in the USA, people seem to attribute different meanings to each. As a Canadian, the British angle is more familiar to me.
Abusage is one term I hope to see not fully reintegrate the English language, although I admit it seems to be making headway (only 100,000 hits on google, not a very used word). I fear Mr. Partridge is on a personal campaign for the word ;p
I suspect if you were to buy and browse his Usage and Abusage, you'd find it an enjoyable read, though you'd have to allow for his unremittingly pompous and superior tone. He's such a scholar, though, that he's pretty much above criticism. You can learn a lot from it.
But... is it really necessary to place 'though' between those commas? Isn't that abusive? ;p
It would have a comma after it if I began the sentence with it, so when I move it to inside the sentence, it gets set off by commas fore and aft. So, yes, it's necessary. Additionally, since the sentence says much the same thing without "though," it's an interjection.
I would never start that particular sentence with though. Read this :)
This situation just goes to say, there are situations which have obvious and agreed upon rules, but the very nature and history of the English language lends itself to argumentation even among grammarians :)
On topics where even grammarians argue... I try not to take sides :)
Let's make a distinction between written English and conversation. I (or even you) might follow up a prior sentence with a sentence beginning with "though" in normal dialog, but we might not write a sentence like that in a term paper.
You have to know the rules to be effective when breaking them, I think. Coloquial language is different to a more formal, written work, as you say. If you adhered to all the rules when speaking informally, I think you'd potentially sound stilted and pedantic. Though not always :-)