Yes that is true, but there may be residuals that give hints to the base pair sequence. If each cell has 20-40 hints and you have millions of cells to work with, there may be enough to deduce the sequence.
IF they can recover any DNA information at all--which is very doubtful--it will surely show significant similarities with human and other vertebrate DNA. The evolutionarily highly conserved HOX genes are needed during development of all vertebrate embryos to establish the basic bilateral symmetry of the body plan, limbs, and the location of major organs.
I'm afraid I'm extremely skeptical that we'll get anything. We've got 6 billion base pairs in our diploid genomes, dinosaurs were no doubt up there in the billions as well. If we do get anything it would be tiny fragments, probably just a few base pairs long (long enough to code for two or three amino acids in a chain that originally was probably several hundred amino acids long), and completely without context. We wouldn't know what gene they went into and what the reading frame was. Without a proper reading frame it would be hopeless anyway!