Is there any bread-board for smd parts?
Is there any veroboard for smd parts?
The usual solution is something like a breakout board that will plug into a breadboard, or a less-specialized "Schmartboard" (specifically designed to be easier to solder.) Such stuff appears all over Tindie. Of course, if you were moving to ARM for lower cost, these "extras" would blow your budget.
Do the ARMs have ADC/DAC built-in?
Yep.
Do they have a large flash+eeprom+ram inside?
Yep.
I just picked an STM32L476 "Discovery" Board (MSRP about $20). The chip has 1M Flash, 128K RAM, 12bit A2D and D2A, 6 uarts, native USB, and more.
Do they run at 5V?
Mostly not, but some do. Atmel has announced a "SAMC" series that has 5V operation. The Cypress PSoC parts will run at 5V...
Are they easy to solder?
It is reported that they're not as bad as they look, assuming you have a pretty high-quality PCB. Which is ok, given that they look awful, and high-quality PCBs are a lot easier to get than they used to be.
The real issue shows up when your program stops fitting in an ATmega328, or you need some modern peripheral like USB or Ethernet. Then you're pretty much stuck with SMT and 3.3V anyway, and you get to decide whether you're going to bite the bullet, or deal with module-level components (Pro Mini, Teensy, Maple Mini, etc, etc. All similarly priced.)
All that said, there is little reason to "retire" the 328 for those problems that don't stress it...