Is she biding her time, or have plate movements reduced the supply of magma?
I came across this volcano while rummaging around the internet to research Tolbachik. A quick Google around for Nachikinsky does not find much; and, she is not listed in GVP. Most of this post is based on a comprehensive study carried out by Portnyagin et al  on the primitive lavas of the Central Kamchatka Depression (CKD).
Nachikinsky is a group of cinder cones at the northern end of the CKD, close to some of the world’s most active volcanoes. It is the tectonic setting which makes this volcano interesting (at least to me).
The dominant tectonic activity in the region is the subduction of the Pacific Plate under the Okhotsk Plate. To the north of the Aleutian-Kamchatkan triple junction, the plate boundary changes from convergent in the south to strike slip motion in the north. A system of fault zones accommodates the change in plate motions. North of the fault zones, the subduction zone may be extinct.
Nachikinsky is a near the Alpha Fault Zone (FZ) at the boundary between the Okhotsk Plate, Komandorsky Plate and the Pacific Plate.
According to Portnyagin et al , in the Pliocene / early Quaternary, Nachikinsky produced low Fe, medium to low K pyroxene and amphibole andesites and dacites. The most recent late Pleistocene rocks are moderate Fe, high to medium K olivine-plagioclase-pyroxene trachybasalts and basaltic trachyandesites. The primitive magmas have varied compositions: early Quaternary rocks are Si rich, and Fe, Ca and Ti poor; whereas, late Pleistocene rocks have relatively low Si, high Ti and High K trachybasaltic compositions. The latter are unlike other primitive magmas in CKD, indicating that the mechanism for magma generation differs from southern CKD volcanoes. Nachikinsky’s lavas have negligible slab derived components.
Levin et al,2002  studies of mantle tomography suggest that neither the Pacific Plate nor the Komandorsky Plate underlies Nachikinsky. A section of the Komandorsky Plate may have broken off during the Cenezoic sinking into the mantle and triggering a temporary mantle upwelling to fill in the void. (Levin et Al, 2002; Portnyagin et al, 2005a).However, Jiang et al  did not find evidence of a broken off plate segment from their studies to determine the structure of the mantle at the Pacific slab edge under Kachatka. They propose that the mantle flows round the edges of the Pacific Plate in a tear zone. The flows may be something like this (assuming that I have the location of Shisheisky volcano correct from Bryant et al ):
From EMSC , we can see that the area has not had many earthquakes greater than 4.5; only a handful have been recorded near Nachikinsky in the past five years, one of which had a magnitude of 6.1. Beachballs for the area show that there is still some residual movement north of the Aleutian FZ:
References & Sources:
1. Portnyagin et al: “Geochemistry of Primitive Lavas of the Central Kamchatka Depression: Magma Generation at the edge of the Pacific Plate”, Maxim Portnyagin, Ilya Bindeman, Kaj Hoernle and Folkmar Hauff, Geophysical Monograph 172, volcanism and subduction: the Kamchatka region. American Geophysical Union, Washington, 199-239, 2007.
2. Levin et al: “Seismic Evidence for Catastrophic Slab Loss beneath Kamchatka”, V. Levin, N. Shapiro, J. Park and M. Ritzwoller, Nature, 418, 763-767, 2002.
3. Jiang et al: “Seismic Tomography of the Pacific Slab Edge under Kamchatka”, Guoming Jiang, Dapeng Zhao and Guibin Zhang, Tectonophysics 465 (2009), 190-203.
4. Bryant et al: “High Mg# Andesitic Lavas of the Shisheisky Complex, Northern Kamchatka: Implications for Primitive Calc-alkaline Magmatism”, J.A. Bryant, G.M. Yogodzonski, T.G. Churikova, Contributions to Mineralogy and Petroloy, Volume 161, Issue 5, 791 – 810.
5. EMSC: http://www.emsc-csem.org/Earthquake/