The link posted above explains what UA's own MP members get.

Try this usairways.com link that compares the new US program's benefits.

Yes, according to this, you should end up as *A Silver as a US Silver Preferred member. The new benefits part of the chart doesn't explicitly say that, but since the current benefits portion shows DM Silver as being *A Silver, then it's extremely likely you'll have *A Silver under the new program.

Probably the reason they don't explicitly list the 2006 program's *A level is uncertainty about whether Gold Preferred will still get *A Gold now that there are 4 DM Preferred levels instead of 3. It wouldn't surprise me if 2006 DM Gold members are dropped to *A Silver level, with only the top 2 DM levels getting *A Gold. That would be similar to how over in Skyteam, only the 75,000 mile+ level elites on NW and DL get Skyteam Elite Plus. Since US is a bit cheaper than UA with some of its benefits (don't shoot me, just my opinion which is why I'm UA rather than US) and emulates NW's cuts to some extent (no pretzels in Y), they might just do this.

But as a US DM Preferred lowest-level member, you should automatically get *A lowest-level elite benefits, so no worries! And they've always had access to UA E+ so you should be fine up in the front of UA Y.