Multi-core Processors- limited scalability?

The creators of multi-core processor chips have added additional ALUs but have not improved access to memory. In data intensive situations the problem with additional cores is being able to feed them. The bottleneck is access to memory. Eventually, as you add more cores, you cannot keep them all busy because some of them will be waiting on a memory fetch at any given time. As the number of cores increase, the effect of this bottleneck increases.  Thus as the number of cores increase we receive less return on each core until we have no additional benefit and most likely