Some people are comparing Navi 14 to Polaris 10 and being disappointed by the relatively minor (~20%) performance uplift. Yes, I've been reading some dumbass comment sections again. I really should stop doing that. Anyway, I wanted to make a post on this subject so here it is.
Navi 14 is not the successor chip design to Polaris 10. Navi 14 actually succeeds Polaris 11 (Baffin), which powers the RX 460 and 560 series. In terms of die size and configuration. Navi 10 is the successor chip to Polaris 10 (not Vega 10). In AMD's historical GPU 'class'. Let's compare them.
Update (18-03-2021): RDNA2 is weird, but the classes remain similar. Bus width is no longer applicable as all parts went down a tier with inclusion of the IFC, except N23 which is still "entry tier". Navi 24 is probably inserted below this to offset the increase in transistors + size + power RDNA2 brought, for entry-level mobile cards.
Mid-size class
Polaris 10/20/30:
~232 mm² @ 14nm
5.7 billion transistors
256-bit GDDR5 Memory Interface
36 CU (2304 SP)
150-220W
Navi 10:
~251 mm² @ 7nm
10.3 billion transistors
256-bit GDDR6 Memory Interface
40 CU (2560 SP)
180-220W
Navi 22:
~330 mm² @ 7nm
17 billion transistors
192-bit GDDR6 Memory Interface + 96MB IFC
40 CU (2560 SP)
~220W
High-end Class
Vega 10:
~495 mm² @ 14nm
12.5 billion transistors
2048-bit HBM2 Memory Interface
64CU (4096 SP)
~250W
Navi 21:
~500 mm² @ 7nm
~26 billion transistors
256-bit GDDR6 + 128MB IFC
80CU (5120 SP)
250-300W
Entry Class
Polaris 11:
~123 mm² @ 14nm
3 billion transistors
128-bit GDDR5 Memory Interface
16 CU (1024 SP)
75-90W
Navi 14:
~158 mm² @ 7nm
6.4 billion transistors
128-bit GDDR6 Memory Interface
24 CU (1536 SP)
120-130W
Navi 23: (Speculation)
~230 mm² @ 7nm (?)
11-12 billion transistors (?)
128-bit GDDR6 Memory Interface + 64MB IFC (?)
32 CU (2048 SP) (?)
120-150W (?)
Here is my arrangement of these Polaris, Vega and Navi. As you can clearly see, the Navi 14 chip is in the same class as the Polaris 11 chip, in terms of size, memory configuration and compute unit count. I'd like to also point out, that successor chips tend to have almost twice the transistors, that represents some form of Moore's Law and progress of performance.
Replacement is not Succession
Navi 14 will 'replace' Polaris 10 / 20 / 30 tier performance, but at a lower price and lower power draw. It is not the successor to that chip, so don't think AMD has basically not pushed the envelope with Navi. If you want to compare progression with Navi, you may compare Polaris 10 (RX 480) with Navi 10 (RX 5700 XT) and see that the performance uplift often in excess of 2X, with only slightly higher power consumption.
Likewise, Navi 10 'replaces' Vega 10 in terms of performance at a lower price (it is slightly faster ~20%) but it does not succeed Vega 10. Navi 21 succeeds Vega 10 with more than twice the transistors and a similar die size (higher density due to moore's law, ish, and power envelope).
Update: Updated on 18/03/2021 with actual specs for Navi 21 and 22. Navi 23 remains speculation.