I wouldn't expect any EoL on the 49xx series just yet. Cisco just released the 4900M, and the earlier 4948s are still mighty potent. (Also there's the new 4500 siblings.)

The most similar pair, for ports and performance, would be the 48 port 3560E and the 4948 10GE. Both have about the same Mpps rate (101/102 Mpps), the 4948 has 136 Gbps fabric vs. the 3560E's 128 Gbps fabric. (The 3750E is about the same as the 3560E except for its stacking capability.)

Choosing between using a 3560E or a 4948 10GE for a top-of-rack device might be determined by the other differences, such as the features of the software, and hardware. Versus just the one 4948 10GE, you have the 24 gig ports plus dual 10 gig 3560E models, 48 gig ports plus dual 10 gig 3560E models, 12 10 gig ports 3560E model and the 12 SFP gig ports plus dual 10 gig 3560E model. (The new 4900M has dual module slots that support either 20 gig, 4x10 gig, or 8x10gig.) The 4900 series also has dual power supplies.

Instead of top-of-rack, if we consider a server row, you might normally chose a chassis such as the 45xx or 65xx. Here, though, is where the 3750E becomes interesting, since they can be stacked. Consider an original 45xx offers only 6 Gbps to each slot (although fabric), and a 65xx using classic cards has a shared 32 Mbps bus with only 15 Mpps, a small (2 or 3) 3750E stack might provide better performance than a 45xx, and a large 3750E stack might provide better performance than a 65xx with classic bus cards.

Another wrinkle, not all servers demand full wire speed performance, whether top-of-rack or server block edge. For less demanding usage, the non-"E" 3560 and/or 3750 might be considered.