Yeah, for now seems likes most radios also support analog FM, so that should be good for "compatibility". Motorola seems to be pushing for DMR P25 P2 and probably TETRA overseas, truth is when manufacturers support a variety of modes, they usually end up winning b/c they force their user base to buy compatible gear to they can operate their other "supported" digital modes... a radio that can do it all is probably not a business savvy decision... b/c if the make the XPR7550e speak P25, the APX series might suffer in sales.. etc..
Here pretty much hoping DMR wins due to the dual timeslot tdma, which allows for two concurrent voice calls without requiring additional frequency space... and radios are affordable and plenty available too, CCRs have their use for cheap floor intercom usage...
I was able to tinker with Echolink with my TM-V71a radios, and you can also link analog radios using that.
Like you've stated, digital modes have their advantages, and DMR isn't meant for discovering new people over the air like say, SSB is, DMR is meant for organizations which require a more precise of radio usage, to know who is talking, etc, and to avoid external people from trying to "open the squelch" and say dumb things, with the added benefit of true digital encryption.
Everybody has their favorite digital mode. There are enough of them, D-Start, DMR, P25, NXDN and Yeasu's System Fusion to name a few. The fly in the ointment is which "standard" will be the majority of people end up using? Bet wrong and you end up with a radio with dwindling support. So far I haven't seen, or know about, a small hand held radio that offers more that one digital mode. Thus if you use more that one mode you end up with a separate radio just for it.
The next issue depends on the digital mode. While radio to radio contacts are basically straight forward going through a repeater is not. The problem is some digital modes may not be compatible with old analog repeaters. The old analog repeater has to be replace at the owners expense with digital compatible equipment.
One of the attractions of digital modes is the ability to link repeaters together over the Internet using various VOIP protocols. That requires access to a high speed Internet connection and a sizable infrastructure to handle the VOIP packet routing etc. like routers and gateways, Then there is the need to register to get you own unique ID so your radio can be identified within the digital network and the VOIP traffic routed to it.
Digital modes are a lot of fun and have their advantages. One just has to understand what maybe involved and plan accordingly. 8-))