Competition for going USMC will likely increase over the next few years. To my (limited, so take with a grain of salt) knowledge, the numbers that HQMC wants from each commissioning source are set out fairly far in advance.
What I mean by that is my class was getting accurate indicators of what our USMC numbers were going to look like from Plebe Summer on. What this means for you is that the Marine Corps is in a drawdown right now and other commissioning sources (post-college OCC and PLC in particular) are already feeling the hurt. This may carry over to Marine selection out of USNA.
Don't let that dissuade you. If you want it, you can make it happen.
From the prospective of wanting infantry...keep in mind that getting USMC is no guarantee for getting infantry. You will have to compete for an MOS at TBS with all of your peers from USNA as well as your compatriots from PLC/OCC (if there even is going to be OCC active...)/NROTC-MO.
For my current TBS class and at least the past few TBS classes ahead of us the numbers for infantry and other combat arms have been high. But, it is very possible to not get it if your performance isn't up to par, the staff doesn't think you should go infantry, or, more rarely, the numbers are just not in your favor due to the thirds system of MOS selection. Supposedly, and I have nothing that's not anecdotal data to back this up, USNA grads go into the combat arms MOSs in disproportionately large numbers.
USNA does offer two ways into special operations much faster than USMA: SEALs and EOD are both available at service selection and USNA grads traditionally do disproportionately well training for those fields. Also, the first tour for Marine ground intelligence officers is also often as a Scout/Sniper platoon commander and Recon/MARSOC is usually available after your first platoon commander tour.