I am by no means an expert in x86 architecture but it seems to me that this avalanche of exploits makes sense for several reasons:
1) This type of exploit, speculative execution exploits, had not previously been used. And so with the first instance of these attacks there has been massive interest in what other ones are possible
2) Intel had a larger share of the market and so offered a bigger target
3) Intel had a much more mature architecture, and had made massive IPC gains through speculative execution to improve the efficiency of their pipeline
4) this one is pure conjecture but maybe the ring bus architecture is more vulnerable to this type of exploit because of the way each core is connected to the cache
So if anything i would say there are only going to be more of these exploits, each with their own name