AMD purchasing Xilinx is a reaction to Intel purchasing Altera five years ago. Dr. Su might be a good CEO for other reasons, but this isn't something that illustrates brilliant strategy on her part.
I think it's more a reaction to the decreasing importance of CPUs in the datacenter in favor of interconnect technology. FPGAs are one of the directions in which the "smart nic" or "DPU" tech has been moving, which is critical to the trend of datacenter disaggregation. Xilinx has a very strong offering in that regard.
If you look at market data, you can see that this market did not exist a few years ago and is now estimated to be worth billions, with major players releasing products in the space. Unless the dynamics pushing this forward change overnight, I think it's pretty safe to call it a trend.
A large reason for the deal with Altera was that Altera already used intel for fabrication. I understand Intel's 10nm and 7nm failure has hurt them a lot in that regard, quite the opposite of the expected synergy. Unlike Xilinx for AMD, they didn't really have any other technologies intel needed either, the biggest advantage was fabrication and that fell through.
Xilinx had laid off a good chunk right before their sale to AMD. Xilinx was having some financial troubles; when that happens, investors want out before a company craters. So selling themselves was one possible solution.
The industry doesn't move overnight. AMD might have seen where Intel was going and didn't want to be caught off guard, or that might be the alternative to Apple approach of dozens of coprocessors on a chip.