I'm interested in what you mean by this. I was working at Altera at the time the acquisition went through, on the software tools mind you, but I didn't notice a significant shift in strategy. Are you referring to before or after the acquisition was announced?
Generally, during and after a merger, there is a lot of instability in a company as layoffs in comparable departments get figured out and company infrastructures get merged. I assume that on the software side, you were insulated from this instability since they were going to need to keep developing Quartus (or its replacement) either way and Intel had no equivalent.
I was an Altera customer before and during the merger (including after it was announced). It looked from the outside like sales teams and chip design teams had significant amounts of instability. I personally experienced months of delays getting Arria 10s (and associated FAE support) from our sales team immediately after the acquisition. Our new sales team from Intel (figured out 8 months later) was twice the size, had to push CPUs and Intel's software in addition to FPGAs, and was also dealing with the embarrassing situation around Stratix 10 delays.
The delays surrounding Stratix 10 were indeed embarrassing, but I'm not sure how much of that was due to the switch to the Intel foundry vs architectural features new to S10.
I can't speak at all for sales/FAE support, but I guess that was a target ripe for "synergy", or w/e they call it.
Basically if AMD dont do anything to Xilinx, leaving it to them continue on their own, both Xilinx and AMD will gain benefits on design cost reduction. Which is important considering leading edge design cost is forever increasing.