I would love to see Lamela here! Even if it makes me a bit sad to see Vucinic leave, since i really like the guy and think he is a great player, it could be the right time to let him go and try to get as much value for him as possible. There are, off course, not guarantees for Lamela, he could turn out to be a flop, but i think he is the kind of player worth a "gamble". I would reckon though, that his price should be around 20-25 million €, since he has not really taken his chance in Spurs, have been injured and apparantly wants to go back to Italy. Furthermore, i would value Vucinic around 12-15 million € in such a swap (might be a bit high, but i think that valuation is fair, since he is much more proven than Lamela, is what Tottenham needs, and could slot in from day one - hence no "potential" to chase before he can make a difference), and i think we should aim for something around Vucinic + 12 million € for the guy... No higher than 15 in my book, since that would be overpaying. It's not like Vucinic is crap and he is not that old. It could turn out to be quite a good investment in the long run though, i certainly rate Lamela, and i think he could fit in both our 3-5-2 and a 4-3-3 or whatever our alternative will look like.
With Vucinic gone, we do need a type, who is capable of taking the fights up front in my opinion. If he leaves, we will only have Llorente, out of five strikers, who can play that kind of role. So if the Vucinic-Lamela swap is actually happening i think we should try and sell one of Giovinco and Quaqliarella (depending on, which of the players we could get a fair deal for, depends on the demand really), and bring a striker, who could play a role similar to the ones Llorente and Vucinic have had (I know there are differences between those two, but they have a bunch of similar tasks when on the fields, fitted to their skills and style off course).
As an alternativ, if we intend to be more flexible between formations, we could sell Quaq and bring in a winger. A guy like Griezmann would be the dream, but maybe we should look for someone with some defensive qualities aswell. If we are to deploy a 4-3-3 with Llorente in the center, i reckon the left wing would be Tevez/Lamela/Giovinco, and with those, especially Lamela and Giovinco, we would need a guy in the other side, who can balance things a bit - if we could somehow get someone with Pepe-esqe characteristics, just better. Di Maria would make my pants wet, but as with Griezmann, it's not just that easy... De Bruyne could be an option, i heard he wants out of Chelsea - and not on loan. Even though he should prefer the Bundesliga, i'm sure we would have a chance competing with teams like Leverkusen and Wolfsburg.
Having a strikeforce (offensive players, for the two striker roles in 3-5-2 and the front three in a 4-3-3) of Llorente, Tevez, Lamela, De Bruyne and Giovinco would be pretty sweet, although i really would like us to have an alternative to Llorente that is not Tevez. Take out Giovinco and add Griezmann/Di Maria or someone like that, and we have an unrealistic dream, but a wet one for sure. I do think though, with our defenders and midfielders in mind, that we should still deploy the 3-5-2 as one of our alternatives, which is why i would like incoming transfers to be able to fit this formation aswell.. (Lamela could play in the front two, both with Llorente and Tevez IMO, and De Bruyne could both be used on the wing back, especially in games where we dominate, and i even see him being able to slot in at midfield if we were so unlucky to have some kind of injurie-nightmare, which is always nice - i know it's not a role where he would be sweet).