Interesting. The difficulty is that almost none of your information is in the public domain, or even known by Staff. This means that you are either somebody fairly high up in the Tfly management chain (i.e. at strategy level), or that you know somebody who is, or that you have heard some rumours, combined them with a little bit of knowledge and have a manner of writing that implies a higher degree of insight than you actually have.
As it stands at the moment, there are no orders for 787 - End of story. If there are orders, then they are a well kept secret. Given the desire to integrate the fleet with HLX and all the other TUI Euro sister carriers, the decision as to the future fleet is complex, and not yet made. The 787 has not been designed as an exclusively longhaul aircraft, and if purchased, the sums would need to add up for shorthaul operations as well (as with 767's in the past). You may believe (as I do) that the 787 is the most likely candidate, but you cannot know this for sure unless you are on the TAM board.
Speculation about US airlines folding or being protected (Chapter 11) and 787 delivery slots being taken up - is pure speculation.
An Engineering move to DSA? Speculation. LAE's don't grow on trees, and there's a chance that one or two of them may find the LTN-DSA commute a bit tedious on a daily basis.
Moving the CC Training facility to DSA? Speculation. It is possible, and also possible that a satellite training facility (to EMA) could be located there - I have no idea, but more importantly, neither do you.
DSA sales? I don't know for sure, since this information is actually held by Thomson - Tfly staff don't know, so how come you do?
If he/she doesn't mind, I'll remind us all of the most IMHO eloquent and accurate phrase used so far in this thread:
Originally Posted by shlittlenellie
Very authoritative stuff, although more than a fair dollop of tosh.
...
Rumours yes, facts or close to the truth - no.