In my opinion, the short answer is no. There's a lot more to building a defense than simply the front seven, and this needs to be taken into account. Also, I think that we need to do a better job identifying stop gaps and core players. Here's my two coppers on the matter:
During the height of the NE defense, it had the best defensive line in the NFL. One could even make a case for the greatest 34 D-Line in league history. That level of dominance is rare. With the proliferation of the 34, and more specifically the 2-gap 34, it is becoming increasingly more difficult to find top tier tallent late in the draft. So, you make due with what you have and add situational players like Pryor until you have an opportunity to take a legit fit difference maker. Wilfork and Warren are still the best in the NFL at their respective positions, and this is often overlooked.
The backers need to be improved. No doubting this. That said, they are only a Mike and a Sam away from being a damn fine group. Jerod Mayo is a prototypical 34 Will. He would be marginally less effective as a 43 Mike. Guyton in respect to the current roster is better suited as a 43 Will, but has enough sand to be effective situationally in the 34. He's basically a Tampa-2 Mike, and is a very solid passing situation backer. I like McKenzie as a 34 Mike or 43 Sam, but I think he is a little too tight in the hips for the 43. I like him a lot in the 34. Outside, I think TBC is a decent Jack/Joker but the team could use a better athlete there to counter the spread heavy offenses that are multiplying like jackrabbits around the league. They need a Sam.
The defensive backfield, however, is the best indicator of intent. Bodden: press corner. Butler: ditto. Meriweather: Prototypical 34 FS. Chung: Prototypical 34 SS. One of the most important positions in the 34 is the SS. Considering the responsibilities of the Sam backer, the SS is a cornerstone of the defense. They play the TE a lot, play alot of run support, cover a large zone, and are tone setters. Chung is a perfect fit for this position, and would be really poor in a 43. Last year's draft said it all.
Finally, the 34 is the thinking man's defense. It is also the most flexible D in respect to personell. Special teams, situational roster, defensive calls, all are exponentially more flexible when the team is built around the 34. Can they play the 43? Absolutely. Are they clearly designed to be a 34? Yes.