Shanks wants to meet luffy - yes but that doesn't mean he wants to fight luffy
Shanks intends to go after one-piece - made one statement but he already made move to go after BB (went wano for him)
Luffy wants to fight shanks - Luffy also wanted to fight BM - and we know who defeated BM
Shanks intends to go after Barto - meh Barto is small fry. His major focus is BB. He is even gathering intel on BB and you think shanks a yonkou will prefer going for Barto over bB.
One comment about BB? Lol
He made 4 specific references to Blackbeard and I am not counting him going to Gorosei to talk about a pirate.
And, same thing can be said to your logic of "Shanks want to go after one piece" after all he made just one comment regarding it.
And, why oda will offscreen shanks vs BB? It will be on -panel. It might get interrupted but it will happen
Ive responded to most of your comments like this ad nauseum, and it gets us nowhere because both sides are subjective and nobody changes their opinion out of bias, so Ill just respond to your last point: Why?
Why would you want them to clash and it be interrupted? What do you get out a useless clash? Be honest, because the one thing I always see is the motivation for BB to kill Shanks. If thats not the case, then would you even want them fighting in isolation from Luffy?
Oda will certainly offscreen the majority of the fight, because thats what he does in virtually every scenario where its not a one shot and doesnt involve the crew in a situated arc. Just like he did for Law and Blackbeard, just like hes likely doing for Garp and Kuzan. Oda has a pretty standard policy of not spoiling full fighting styles or movesets from characters who havent been shown off yet. This has never changed in nearly 3 decades.
And to that point, its not just Shanks and Blackbeard, but all of their commanders. Do you think Oda can justify Teach's side defeating all 10 or 11 main RHP members onscreen? Like I said, he doesnt spoil fights before Luffy is involved, so this will heavily skew to an offscreen. Can he justify defeating them offscreen lol? Again, be honest.
Now I come back to your main point: someone will interrupt them. Who? How? Why? Who can actually stop 2 Yonko from fighting? How would Oda justify it? Why do you even want an interruption?
This is exactly why I cannot see them clashing before Luffy meets both of them. Its better to just assume Shanks and Blackbeard will be part of the same arc, similar to Kaido and BM (or one is featured earlier first I guess).