I imagine VDB is trying very hard behind the scenes to get Laporte too. Or at least he should be.
If they get Laporte and/or Lucas, with Vallejo coming through, I think they'll be in pretty good shape again. Javi Martinez is still only 27 too so (barring injury) he'll be around for a bit while those guys develop.
There is a lot of hypotheses in this post ,I highly doubt Laporte is even considering Spain that much .he is French and he was clear about it .Playing for NT is about pride more than anything and while there are many Diego Costa there are way more players who are attached to their NT .
Laporte will get his chance once the Euro is over .Mathieu will be out and Koscielny won't stay with them for long and it will open the room for this new generation of him & Zouma to take over with Varane and Sakho .
Javi is playing CB in a Pep(and Bielsa b4 him) system .but under Ancelotti? very doubtful IMHO .he will return to his best position by far which is DM and there is a reason they are looking for a new CB with Benattia declining form .seem they are linked to players like Hummels & Mustafi
No one knows how good is Vallejo ,for now he is just a hyped kid just like Inigo Martinez and Bartera b4 him .the only bright spot for Spain would be Lucas as he is already look better than anything they have other than Pique & Ramos
The real good news is that Pique and Ramos could easily remain CB partners for 2020 .so they have time to look for the next big CB